Academia.eduAcademia.edu

Outline

Title
Abstract
Key Takeaways
Figures
Introduction
Case Studies
References
All Topics
Engineering
Materials Science

Solution-processed image sensors on flexible substrates

Profile image of Ana AriasAna Arias

2016, Flexible and Printed Electronics

https://doi.org/10.1088/2058-8585/1/4/043001
visibility

…

description

27 pages

link

1 file

Abstract

Copper(I) thiocyanate (CuSCN) as a hole-transport material for large-area opto/electronics

Key takeaways
sparkles

AI

  1. Solution-processed image sensors utilize flexible substrates, enhancing scalability and reducing costs compared to silicon.
  2. Active-switching architectures improve signal-to-noise ratio (SNR) by enabling intra-pixel charge integration.
  3. Large pixel areas are crucial for performance, particularly at higher frame rates and shorter integration times.
  4. Figures of merit like external quantum efficiency (EQE) and specific detectivity (D*) assess photodiode performance.
  5. Dynamic range is determined by the photogenerated signal's limits, influenced by noise and saturation factors.
Figures (18)
processing cost per unit area of image sensors.
processing cost per unit area of image sensors.
Figure 1. (a) Schematic view of an image sensor depicting the flow of photogenerated charge from charge integration in the pixel (step 1), to discharging in the column for either passive or active pixels (step 2), and finally readout from external circuits sensing voltage, charge, or current (step 3). (b) Rolling shutter addressing and readout scheme. (c) Global shutter addressing and readout scheme.
Figure 1. (a) Schematic view of an image sensor depicting the flow of photogenerated charge from charge integration in the pixel (step 1), to discharging in the column for either passive or active pixels (step 2), and finally readout from external circuits sensing voltage, charge, or current (step 3). (b) Rolling shutter addressing and readout scheme. (c) Global shutter addressing and readout scheme.
Figure 2. Upper and lower bounds on the dynamic range of a photogenerated signal starting from generation in the photodetector, to storage in the pixel, and finally readout on the column line after discharge form the pixel. of the dark current or 1/fnoise caused by trap states in the device. The main limiting factor in the dynamic range of an image sensor arises when the photo- generated signal from the photodetector is captured and stored in the pixel circuitry. The capacitive ele- ment used for photocharge integration can only store a finite amount of charge for a given supply voltage (Q = CV), known as the well capacity. However, parasitic capacitances between transistors and the charge integration node severely deteriorate perfor- mance. Row and column lines, which are connected to transistor terminals, induce parasitic charge injection into the path of the photogenerated charge, which not only decreases well capacity but also raises the noise floor. Pixel-to-pixel leakage can also become a limiting factor for the noise floor of image sensors when charge bleeds into the adjacent pixels, known as blooming. Consequently proper pixel—pixel isolation is needed in order to ensure that the noise floor of adjacent dark pixels does not become limited by blooming. Poor optics and fill factor, the percentage of the pixel’s area that is photosensitive, also limit the amount of light reaching the photodetector element. In the final step, the integrated photocurrent is discharged from the pixel onto the column and read by the readout cir- cuitry. Parasitic capacitance between the column and driver lines should be minimized as it can result in sig- nal saturation at the readout and also noise. The design of the readout circuitry must avoid signal saturation by the well capacity of the pixel. Variability in the dark current, known as fixed pattern noise, must be kept at a minimum in order to establish a consistent back- ground noise throughout the whole array. In order to advance the field of solution processed large area image sensors, it is imperative to perform an assessment on the state-of-the-art of these systems with regards to photodetector devices, image sensors of various pixel architectures, and imaging optics. In this review, the theory, figures of merit and state-of- the-art of photodiodes and phototransistors will first be overviewed. Following this, discussion on solution processed image sensors will be organized into passive non-switching, passive active-switching and active pixel systems. Finally, progress in optics compliant with large area and flexible sensors will be reviewed.
Figure 2. Upper and lower bounds on the dynamic range of a photogenerated signal starting from generation in the photodetector, to storage in the pixel, and finally readout on the column line after discharge form the pixel. of the dark current or 1/fnoise caused by trap states in the device. The main limiting factor in the dynamic range of an image sensor arises when the photo- generated signal from the photodetector is captured and stored in the pixel circuitry. The capacitive ele- ment used for photocharge integration can only store a finite amount of charge for a given supply voltage (Q = CV), known as the well capacity. However, parasitic capacitances between transistors and the charge integration node severely deteriorate perfor- mance. Row and column lines, which are connected to transistor terminals, induce parasitic charge injection into the path of the photogenerated charge, which not only decreases well capacity but also raises the noise floor. Pixel-to-pixel leakage can also become a limiting factor for the noise floor of image sensors when charge bleeds into the adjacent pixels, known as blooming. Consequently proper pixel—pixel isolation is needed in order to ensure that the noise floor of adjacent dark pixels does not become limited by blooming. Poor optics and fill factor, the percentage of the pixel’s area that is photosensitive, also limit the amount of light reaching the photodetector element. In the final step, the integrated photocurrent is discharged from the pixel onto the column and read by the readout cir- cuitry. Parasitic capacitance between the column and driver lines should be minimized as it can result in sig- nal saturation at the readout and also noise. The design of the readout circuitry must avoid signal saturation by the well capacity of the pixel. Variability in the dark current, known as fixed pattern noise, must be kept at a minimum in order to establish a consistent back- ground noise throughout the whole array. In order to advance the field of solution processed large area image sensors, it is imperative to perform an assessment on the state-of-the-art of these systems with regards to photodetector devices, image sensors of various pixel architectures, and imaging optics. In this review, the theory, figures of merit and state-of- the-art of photodiodes and phototransistors will first be overviewed. Following this, discussion on solution processed image sensors will be organized into passive non-switching, passive active-switching and active pixel systems. Finally, progress in optics compliant with large area and flexible sensors will be reviewed.
Figure 3. (a) Band diagram of an organic photodiode depicting charge generation and collection and the equivalent circuit. (b) Qualitative depiction of external quantum efficiency (EQE) and responsivity (R) for a photodetector. (c) Typical photodiode current— voltage characteristics in dark and under illumination. (d) Illustration of dynamic range for a photodetector.
Figure 3. (a) Band diagram of an organic photodiode depicting charge generation and collection and the equivalent circuit. (b) Qualitative depiction of external quantum efficiency (EQE) and responsivity (R) for a photodetector. (c) Typical photodiode current— voltage characteristics in dark and under illumination. (d) Illustration of dynamic range for a photodetector.
Two equivalent figures of merit used to express the performance of a photodiode at low irradiances are noise equivalent power (NEP) and specific detectivity (D*). NEP is the theoretical lowest measurable irra- diance (SNR = 1) for a 1 Hz integration bandwidth (or equivalently half second integration time accord- ing to Nyquist-Shannon sampling theory [5]). Figure 3(d) qualitatively shows that the NEP marks the lowest point on the dynamic range. NEP can be quan- tified by equation (4), which is the noise spectral den- sity divided by the responsivity of the photodiode. Specific detectivity is defined by equation (5) and is inversely proportional to NEP and normalized to area (A) since Sx VI x VA. This area normalization is important in order to allow a fair comparison between various photodiodes since, as previously discussed, SNR increases with area Two equivalent figures of merit used to express the
Two equivalent figures of merit used to express the performance of a photodiode at low irradiances are noise equivalent power (NEP) and specific detectivity (D*). NEP is the theoretical lowest measurable irra- diance (SNR = 1) for a 1 Hz integration bandwidth (or equivalently half second integration time accord- ing to Nyquist-Shannon sampling theory [5]). Figure 3(d) qualitatively shows that the NEP marks the lowest point on the dynamic range. NEP can be quan- tified by equation (4), which is the noise spectral den- sity divided by the responsivity of the photodiode. Specific detectivity is defined by equation (5) and is inversely proportional to NEP and normalized to area (A) since Sx VI x VA. This area normalization is important in order to allow a fair comparison between various photodiodes since, as previously discussed, SNR increases with area Two equivalent figures of merit used to express the
Figure 4. (a) Organic blocking layers in a Perovskite photodiode and its dynamic response. (b) Filterless organic photodiodes enabled through thick active layers and the resulting EQE spectrum. Reprinted with permission from Macmillan Publishers Ltd: Nat. Commun. [20], copyright 2015. (c) Detectivity as a function of applied field across the device for various photodiodes cited in this review along with the bias stress stability of an organic photodiode. (a) and (c) Reprinted with permission from [22] and [36], respectively. Copyright 2015 John Wiley and Sons.
Figure 4. (a) Organic blocking layers in a Perovskite photodiode and its dynamic response. (b) Filterless organic photodiodes enabled through thick active layers and the resulting EQE spectrum. Reprinted with permission from Macmillan Publishers Ltd: Nat. Commun. [20], copyright 2015. (c) Detectivity as a function of applied field across the device for various photodiodes cited in this review along with the bias stress stability of an organic photodiode. (a) and (c) Reprinted with permission from [22] and [36], respectively. Copyright 2015 John Wiley and Sons.
Figure 5. (a) Hole (red) and electron (yellow) movement in a hole-transporting phototransistor with photoconductive gain and the dynamic response shown to the right. (b) Charge carrier movement in the same phototransistor but operating in a long-term charge- trapping regime.
Figure 5. (a) Hole (red) and electron (yellow) movement in a hole-transporting phototransistor with photoconductive gain and the dynamic response shown to the right. (b) Charge carrier movement in the same phototransistor but operating in a long-term charge- trapping regime.
Figure 6. (a) Interfacial trapping of photogenerated carriers used to inject charge from an electrode as a gain mechanism. Reprinted with permission from Macmillan Publishers Ltd: Nature Nanotechnology [40], copyright 2012. (b) Broadband bulk heterojunction phototransistor. Reprinted by permission from Macmillan Publishers Ltd: Sci Rep. [54], copyright 2015. (c) Fabrication steps for an all-printed phototransistor. Reprinted from [57], copyright 2014, with permission from Elsevier.
Figure 6. (a) Interfacial trapping of photogenerated carriers used to inject charge from an electrode as a gain mechanism. Reprinted with permission from Macmillan Publishers Ltd: Nature Nanotechnology [40], copyright 2012. (b) Broadband bulk heterojunction phototransistor. Reprinted by permission from Macmillan Publishers Ltd: Sci Rep. [54], copyright 2015. (c) Fabrication steps for an all-printed phototransistor. Reprinted from [57], copyright 2014, with permission from Elsevier.
Figure 7. (a) Photodiode and (b) phototransistor-based passive pixel architecture for image sensors not using intra- pixel charge integration.
Figure 7. (a) Photodiode and (b) phototransistor-based passive pixel architecture for image sensors not using intra- pixel charge integration.
Figure 8. (a) Reproduced color image scanned by a linear array of organic photodiodes. Reprinted with permission from [61]. Copyright 1998 John Wiley and Sons. (b) An array of phototransistors based on charge transfer to a semiconductor from a light- absorbing dye. Reprinted with permission from [65]. Copyright 2016 American Chemical Society. (c) Light-programmable organic phototransistor memory devices and an imaging array. Reprinted by permission from Macmillan Publishers Ltd: Sci Rep. [46], copyright 2013.
Figure 8. (a) Reproduced color image scanned by a linear array of organic photodiodes. Reprinted with permission from [61]. Copyright 1998 John Wiley and Sons. (b) An array of phototransistors based on charge transfer to a semiconductor from a light- absorbing dye. Reprinted with permission from [65]. Copyright 2016 American Chemical Society. (c) Light-programmable organic phototransistor memory devices and an imaging array. Reprinted by permission from Macmillan Publishers Ltd: Sci Rep. [46], copyright 2013.
Table 1. Properties of solution-processed non-charge-integrating passive pixel image sensors.
Table 1. Properties of solution-processed non-charge-integrating passive pixel image sensors.
Figure 9. (a) 1 T pixel architecture, a charge-integrating passive pixel, showing the integrating capacitor of the photodiode (Cpp) and parasitic capacitances. (b) Drive voltage (V<), photodiode node voltage (Vpp), and charge on the column line (Q-) during pixel operation with parasitic effects.
Figure 9. (a) 1 T pixel architecture, a charge-integrating passive pixel, showing the integrating capacitor of the photodiode (Cpp) and parasitic capacitances. (b) Drive voltage (V<), photodiode node voltage (Vpp), and charge on the column line (Q-) during pixel operation with parasitic effects.
Table 2. Properties of solution-processed passive pixel image sensors capable of intra-pixel charge integration.
Table 2. Properties of solution-processed passive pixel image sensors capable of intra-pixel charge integration.
Figure 10. (a) Monolithic integration of an organic thin film transistor (TFT) and organic photodiode (OPD) to forma 1 T pixel along with the dynamic response. Reprinted from [78], copyright 2011, with permission from Elsevier. (b) Flexible organic photodiode- carbon nanotube TFT 1 T image sensor. Reprinted with permission from [73]. Copyright 2013 American Chemical Society. (c) Top- illuminated spray-coated organic photodiodes on top ofa CMOS chip to form a hybrid image sensor. Reprinted by permission from Macmillan Publishers Ltd: Nat. Commun. [80], copyright 2012.
Figure 10. (a) Monolithic integration of an organic thin film transistor (TFT) and organic photodiode (OPD) to forma 1 T pixel along with the dynamic response. Reprinted from [78], copyright 2011, with permission from Elsevier. (b) Flexible organic photodiode- carbon nanotube TFT 1 T image sensor. Reprinted with permission from [73]. Copyright 2013 American Chemical Society. (c) Top- illuminated spray-coated organic photodiodes on top ofa CMOS chip to form a hybrid image sensor. Reprinted by permission from Macmillan Publishers Ltd: Nat. Commun. [80], copyright 2012.
Figure 11. Active pixel architecture of a3 T image sensor, comprised of reset, source follower, and row-select transis- tors. The equivalent circuit of the photodetector is shown, as is the bias current source for voltage readout on the column line.
Figure 11. Active pixel architecture of a3 T image sensor, comprised of reset, source follower, and row-select transis- tors. The equivalent circuit of the photodetector is shown, as is the bias current source for voltage readout on the column line.
Table 3. Properties of solution-processed active pixel image sensors.
Table 3. Properties of solution-processed active pixel image sensors.
Figure 12. (a) Active pixels using light-sensitive resistive voltage dividers to modulate the conductance of an organic thin film transistor are implemented as image sensors. Reprint with permission from [87]. Copyright 2015 John Wiley and Sons. (b) Integration of metal oxide thin film transistors and organic phototransistors to form active pixel image sensors. Reprinted with permission from [88]. Copyright 2016 John Wiley and Sons. (c) Hybrid organic photodetector-CMOS transistor image sensors with high dynamic range. © 2016 IEEE. Reprinted, with permission from [90].
Figure 12. (a) Active pixels using light-sensitive resistive voltage dividers to modulate the conductance of an organic thin film transistor are implemented as image sensors. Reprint with permission from [87]. Copyright 2015 John Wiley and Sons. (b) Integration of metal oxide thin film transistors and organic phototransistors to form active pixel image sensors. Reprinted with permission from [88]. Copyright 2016 John Wiley and Sons. (c) Hybrid organic photodetector-CMOS transistor image sensors with high dynamic range. © 2016 IEEE. Reprinted, with permission from [90].
Figure 13. (a) The Bayer filter pattern, which is most common in commercial image sensors. (b) Vertically-stacked blue-, green-, and red-sensitive pixels in a pixel that are used to form an image sensor. Reprinted with permission from [31]. Copyright 2011 The Japan Society of Applied Physics. (c) A deformable passive pixel image sensor that can conform to the focal surface ofa lens. Reprinted with permission from [99]. Copyright 2011 National Academy of Sciences of the United States of America. (d) Microlens array for thin planar imaging optics. Reprinted with permission from [102]. Copyright 2014 Society of Photo Optical Instrumentation Engineers.
Figure 13. (a) The Bayer filter pattern, which is most common in commercial image sensors. (b) Vertically-stacked blue-, green-, and red-sensitive pixels in a pixel that are used to form an image sensor. Reprinted with permission from [31]. Copyright 2011 The Japan Society of Applied Physics. (c) A deformable passive pixel image sensor that can conform to the focal surface ofa lens. Reprinted with permission from [99]. Copyright 2011 National Academy of Sciences of the United States of America. (d) Microlens array for thin planar imaging optics. Reprinted with permission from [102]. Copyright 2014 Society of Photo Optical Instrumentation Engineers.

Related papers

Variation of the morphology of electrodeposited copper thiocyanate films
Tsukasa Yoshida

Thin Solid Films, 2008

Crystalline CuSCN films can be obtained by cathodic electrodeposition from solutions containing Cu(II) cation and thiocyanate anion. The change in film structure and morphology due to variation of the deposition conditions is investigated in view of applications of CuSCN in dyesensitized p-n solar cells. Smaller grain sizes were obtained towards more negative deposition potentials, with higher ethanol fraction in the solvent and in the presence of dye molecules and surfactants as structure-directing additives. The largest effect was seen when varying the anion of the copper(II) salt and the cation of the thiocyanate salt in the deposition bath. While Cu(ClO 4 ) 2 and LiSCN lead to the formation of compact films, plate-like structures are seen with CuCl 2 and NH 4 SCN and rod-like structures with NaSCN.

View PDFchevron_right
Formation of unique nanocrystalline Cu-In-Se bulk pn homojunctions for opto-electronic devices
Shalini Menezes

Scientific Reports

Semiconductor pn junctions, integrated in optoelectronic devices require high quality crystals, made by expensive, technically difficult processes. Bulk heterojunction (BHJ) structures offer practical alternatives to circumvent the cost, flexibility and scale-up challenges of crystalline planar pn junctions. Fabrication methods for the current organic or inorganic BHJ structures invariably create interface mismatch and low doping issues. To overcome such issues, we devised an innovative approach, founded on novel inorganic material system that ensued from single-step electrodeposited copper-indiumselenide compounds. Surface analytical microscopies and spectroscopies reveal unusual phenomena, electro-optical properties and quantum effects. They support the formation of highly-ordered, sharp, abrupt 3-dimensional nanoscale pn BHJs that facilitate efficient charge carrier separation and transport, and essentially perform the same functions as crystalline planar pn junctions. This approach offers a lowcost processing platform to create nanocrystalline films, with the attributes necessary for efficient BHJ operation. It allows roll-to-roll processing of flexible devices in simple thin-film form factor.

View PDFchevron_right
Highly efficient organic solar Cells based on a robust room-temperature solution-processed copper iodide hole transporter
Abdulrahman Labban

Nano Energy, 2015

Achieving high performance and reliable organic solar cells hinges on the development of stable and energetically suitable hole transporting buffer layers in tune with the electrode and photoactive materials of the solar cell stack. Here we have identified solution-processed copper(I) iodide (CuI) thin films with low-temperature processing conditions as an effective hole-transporting layer (HTL) for a wide range of polymer:fullerene bulk heterojunction (BHJ) systems. The solar cells using CuI HTL show higher power conversion efficiency (PCE) in standard device structure for polymer blends, up to PCE of 8.8%, as compared with poly(3,4-ethylenedioxy-thiophene):poly(styrenesulfonate) (PEDOT:PSS) HTL, for a broad range of polymer:fullerene systems. The CuI layer properties and solar cell device behavior are shown to be remarkably robust and insensitive to a wide range of processing conditions of the HTL, including processing solvent, annealing temperature (room temperature up to 200 1C), and film thickness. CuI is also shown to improve the overall lifetime of solar cells in the standard architecture as compared to PEDOT:PSS. We further demonstrate promising solar cell performance when using CuI as top HTL in inverted device architecture. The observation of uncommon properties, such as photoconductivity of CuI and templating effects on the BHJ layer formation, is also discussed. This study points to CuI as being a good candidate to replace PEDOT:PSS in solution-processed solar cells thanks to the facile implementation and demonstrated robustness of CuI thin films.

View PDFchevron_right
Photoelectrochemical (PEC) Studies on Chemically Deposited CuSCN Thin Film by Simple Chemical Route
Editor CSRL

Chemical deposition method, namely, modified chemical bath deposition (M-CBD) has been used to deposit copper thiocyanate (CuSCN) thin films. The CuSCN thin films were deposited onto glass and FTO coated glass substrates from an aqueous medium at room temperature. To obtain good quality of thin films, preparative conditions such as concentration, pH of precursor solution and adsorption, reaction and rinsing time durations were optimized at room temperature. The structural, morphological, optical, electrical and photoelectronchemical (PEC) properties of the films were investigated. X-ray diffraction (XRD) patterns of CuSCN thin films reveals that the films have a rhombohedral structure. The band gap was found to be 3.9 eV. The PEC studies showed that the material is a wide band gap. PACS: 81.15.- z; 68.55.-a; 78.20

View PDFchevron_right
Thiocyanate-Capped PbS Nanocubes: Ambipolar Transport Enables Quantum Dot Based Circuits on a Flexible Substrate
Weonkyu Koh

Nano …, 2011

View PDFchevron_right
Chlorine-Infused Wide-Band Gap p-CuSCN/n-GaN Heterojunction Ultraviolet-Light Photodetectors
Mohamed Hedhili

ACS Applied Materials &amp; Interfaces

Copper thiocyanate (CuSCN) is a p-type semiconductor that exhibits holetransport and wide-band gap (∼3.9 eV) characteristics. However, the conductivity of CuSCN is not sufficiently high, which limits its potential application in optoelectronic devices. Herein, CuSCN thin films were exposed to chlorine using a dry etching system to enhance their electrical properties, yielding a maximum hole concentration of 3 × 10 18 cm -3 . The p-type CuSCN layer was then deposited onto an n-type gallium nitride (GaN) layer to form a prototypical ultraviolet-based photodetector. X-ray photoelectron spectroscopy further demonstrated the interface electronic structures of the heterojunction, confirming a favorable alignment for holes and electrons transport. The ensuing p-CuSCN/n-GaN heterojunction photodetector exhibited a turn-on voltage of 2.3 V, a responsivity of 1.35 A/W at -1 V, and an external quantum efficiency of 5.14 × 10 2 % under illumination with ultraviolet light (peak wavelength of 330 nm). The work opens a new pathway for making a plethora of hybrid optoelectronic devices of inorganic and organic nature by using p-type CuSCN as the hole injection layer.

View PDFchevron_right
Copper coordination polymers with selective hole conductivity
Gerrit Boschloo

Journal of materials chemistry. A, Materials for energy and sustainability, 2022

Emerging technologies in solar energy will be critical in enabling worldwide society in overcoming the present energy challenges and reaching carbon net zero. Inefficient and unstable charge transport materials limit the current emerging energy conversion and storage technologies. Low-dimensional coordination polymers represent an alternative, unprecedented class of charge transport materials, comprised of molecular building blocks. Here, we provide a comprehensive study of mixed-valence coordination polymers from an analysis of the charge transport mechanism to their implementation as hole-conducting layers. Cu II dithiocarbamate complexes afford morphology control of 1D polymer chains linked by (Cu I 2 X 2 ) copper halide rhombi. Concerted theoretical and experimental efforts identified the charge transport mechanism in the transition to band-like transport with a modeled effective hole mass of 6m e . The iodide-bridged coordination polymer showed an excellent conductivity of 1 mS cm À1 and a hole mobility of 5.8 10 À4 cm 2 (V s) À1 at room temperature. Nanosecond selective hole injection into coordination polymer thin films was captured by nanosecond photoluminescence of halide perovskite films. Coordination polymers constitute a sustainable, tunable alternative to the current standard of heavily doped organic hole conductors.

View PDFchevron_right
Polymer solar cells with electrodeposited CuSCN nanowires as new efficient hole transporting layer
Raul Salazar

Solar Energy Materials and Solar Cells, 2014

and sharing with colleagues.

View PDFchevron_right
Copper Bromide as an Efficient Solution-Processable Hole Transport Layer for Organic Solar Cells: Effect of Solvents
Dinesh Bhardwaj

ACS Omega

In this work, we report copper bromide (CuBr) as an efficient, inexpensive, and solutionprocessable hole transport layer (HTL) for organic solar cells (OSCs) for the first time. To examine the effectiveness of the material in general, three different solvents such as acetonitrile (MeCN), dimethyl sulfoxide (DMSO), and dimethylformamide (DMF) are used for solution-processing thin-film deposition of CuBr. CuBr thin films deposited from different solvents show high transparency and no significant difference has been observed in absorption in the visible and near-IR range, whereas a slight difference has been found in the near-UV range by changing the solvents. Furthermore, two most studied combinations of the active layer such as PTB7/PC 71 BM and PCDTBT:/PC 71 BM are used for device fabrication with geometry of ITO/CuBr(HTL) active layer/Al. By using CuBr as a HTL in OSCs, the power conversion efficiencies (PCEs) have been achieved to up to 5.16 and 4.72% with PTB7/PC 71 BM and PCDTBT/PC 71 BM active layers, respectively. The CuBr film from DMF solvent shows highest PCE as compared to films deposited from DMSO and MeCN solvents. Different solvents used for HTL deposition have a major effect on the fill factor (FF), while very little difference on open circuit voltage (V oc) and short circuit current (J sc) has been observed. It may be mentioned here that a small difference of device parameters (PCE, FF, J sc , and V oc) has been observed in the devices using the HTL deposited from DMF and DMSO solvents, whereas a significant difference of the device parameters has been found in devices using the HTL from MeCN solvent.

View PDFchevron_right
11% efficiency solid-state dye-sensitized solar cells with copper(II/I) hole transport materials
Yasemin Saygılı

Nature Communications, 2017

Solid-state dye-sensitized solar cells currently suffer from issues such as inadequate nanopore filling, low conductivity and crystallization of hole-transport materials infiltrated in the mesoscopic TiO 2 scaffolds, leading to low performances. Here we report a record 11% stable solid-state dye-sensitized solar cell under standard air mass 1.5 global using a hole-transport material composed of a blend of [Cu (4,4 0 ,6,6 0-tetramethyl-2,2 0-bipyridine) 2 ](bis(trifluoromethylsulfonyl)imide) 2 and [Cu (4,4 0 ,6,6 0-tetramethyl-2,2 0-bipyridine) 2 ](bis(trifluoromethylsulfonyl)imide). The amorphous Cu(II/I) conductors that conduct holes by rapid hopping infiltrated in a 6.5 mm-thick mesoscopic TiO 2 scaffold are crucial for achieving such high efficiency. Using time-resolved laser photolysis, we determine the time constants for electron injection from the photoexcited sensitizers Y123 into the TiO 2 and regeneration of the Y123 by Cu(I) to be 25 ps and 3.2 ms, respectively. Our work will foster the development of low-cost solid-state photovoltaic based on transition metal complexes as hole conductors.

View PDFchevron_right

References (110)

  1. Hu C 2010 Modern Semiconductor Devices for Integrated Circuits (Englewood Cliffs, NJ: Prentice-Hall) ISBN: 0136085253
  2. Taur Y and Ning T H 2013 Fundamentals of Modern VLSI Devices (Cambridge: Cambridge University Press) ISBN: 0521550564
  3. Holst G C and Lomheim T S 2007 CMOS/CCD Sensors and Camera Systems (FL, USA: JCD Publishing) ISBN: 0819486531
  4. Street R A 2000 Technology and Applications of Amorphous Silicon (New York: Springer) ISBN: 3540657142
  5. Saleh B E, Teich M C and Saleh B E 1991 Fundamentals of Photonics (New York: Wiley) ISBN: 0471358320
  6. Arias A C, MacKenzie J D, McCulloch I, Rivnay J and Salleo A 2010 Materials and applications for large area electronics: solution-based approaches Chem. Rev. 110 3-24
  7. Krebs F C 2009 Fabrication and processing of polymer solar cells: a review of printing and coating techniques Sol. Energy Mater. Sol. Cells 93 394-412
  8. Herault J, Cristobal G, Perrinet L and Keil M S 2015 Biologically Inspired Computer Vision: Fundamentals and Applications (New York: Wiley) (doi:10.1002/ 9783527680863)
  9. Krebs F C, Gevorgyan S A and Alstrup J 2009 A roll-to-roll process to flexible polymer solar cells: model studies, manufacture and operational stability studies J. Mater. Chem. 19 5442-51
  10. Miyata A et al 2015 Direct measurement of the exciton binding energy and effective masses for charge carriers in organic-inorganic tri-halide perovskites Nat. Phys. 11 582-7
  11. Baeg K-J, Binda M, Natali D, Caironi M and Noh Y-Y 2013 Organic light detectors: photodiodes and phototransistors Adv. Mater. 25 4267-95
  12. Jansen-van Vuuren R D, Armin A, Pandey A K, Burn P L and Meredith P 2016 Organic photodiodes: the future of full color detection and image sensing Adv. Mater. n/a-n/a (doi:10.1002/adma.201505405)
  13. Blom P W M, Mihailetchi V D, Koster L J A and Markov D E 2007 Device physics of polymer: fullerene bulk heterojunction solar cells Adv. Mater. 19 1551-66
  14. Ng T N, Wong W S, Chabinyc M L, Sambandan S and Street R A 2008 Flexible image sensor array with bulk heterojunction organic photodiode Appl. Phys. Lett. 92 213303
  15. Giuseppina P, Andrea G, Marco S, Dario N and Mario C 2015 Printed photodetectors Semicond. Sci. Technol. 30 104006
  16. Chen L M, Hong Z R, Li G and Yang Y 2009 Recent progress in polymer solar cells: manipulation of polymer: fullerene morphology and the formation of efficient inverted polymer solar cells Adv. Mater. 21 1434-49
  17. He Z C, Zhong C M, Su S J, Xu M, Wu H B and Cao Y 2012 Enhanced power-conversion efficiency in polymer solar cells using an inverted device structure Nat. Photon. 6 591-5
  18. Park S H et al 2009 Bulk heterojunction solar cells with internal quantum efficiency approaching 100% Nat. Photon. 3 297-303
  19. Bartelt J A et al 2014 Controlling solution-phase polymer aggregation with molecular weight and solvent additives to optimize polymer-fullerene bulk heterojunction solar cells Adv. Energy Mater. 4 1301733
  20. Armin A, Jansen-van Vuuren R D, Kopidakis N, Burn P L and Meredith P 2015 Narrowband light detection via internal quantum efficiency manipulation of organic photodiodes Nat. Commun. 6 6343
  21. Binda M, Iacchetti A, Natali D, Beverina L, Sassi M and Sampietro M 2011 High detectivity squaraine-based near infrared photodetector with nA cm -2 dark current Appl. Phys. Lett. 98 073303
  22. Fang Y and Huang J 2015 Resolving weak light of sub- picowatt per square centimeter by hybrid perovskite photodetectors enabled by noise reduction Adv. Mater. 27 2804-10
  23. Lin Q, Armin A, Lyons D M, Burn P L and Meredith P 2015 Low noise, IR-blind organohalide perovskite photodiodes for visible light detection and imaging Adv. Mater. 27 2060-4
  24. Arca F, Tedde S F, Sramek M, Rauh J, Lugli P and Hayden O 2013 Interface trap states in organic photodiodes Sci. Rep. 3 1324
  25. Shockley W and Queisser H J 1961 Detailed balance limit of efficiency of p-n junction solar cells J. Appl. Phys. 32 510-9
  26. Gong X et al 2009 High-detectivity polymer photodetectors with spectral response from 300 nm to 1450 nm Science 325 1665-7
  27. Zhou X, Yang D and Ma D 2015 Extremely low dark current, high responsivity, all-polymer photodetectors with spectral response from 300 nm to 1000 nm Adv. Opt. Mater. 3 1570-6
  28. Rauch T et al 2009 Near-infrared imaging with quantum-dot- sensitized organic photodiodes Nat. Photon. 3 332-6
  29. Seo H, Aihara S, Watabe T, Ohtake H, Kubota M and Egami N 2007 Color sensors with three vertically stacked organic photodetectors Jpn J Appl Phys. 46 L1240
  30. Aihara S et al 2009 Stacked image sensor with green-and red- sensitive organic photoconductive films applying zinc oxide thin-film transistors to a signal readout circuit IEEE Trans. Electron Devices 56 2570-6
  31. Seo H et al 2011 A 128 × 96 pixel stack-type color image sensor: stack of individual blue-, green-, and red-sensitive organic photoconductive films integrated with a ZnO thin film transistor readout circuit Jpn. J. Appl. Phys. 50 024103
  32. Zhou Y H et al 2012 A universal method to produce low-work function electrodes for organic electronics Science 336 327-32
  33. Huang F, Wu H, Wang D, Yang W and Cao Y 2004 Novel electroluminescent conjugated polyelectrolytes based on polyfluorene Chem. Mater. 16 708-16
  34. Azzellino G, Grimoldi A, Binda M, Caironi M, Natali D and Sampietro M 2013 Fully inkjet-printed organic photodetectors with high quantum yield Adv. Mater. 25 6829-33
  35. Pace G et al 2014 All-organic and fully-printed semitransparent photodetectors based on narrow bandgap conjugated molecules Adv. Mater. 26 6773-7
  36. Pierre A, Deckman I, Lechêne P B and Arias A C 2015 High detectivity all-printed organic photodiodes Adv. Mater. 27 6411-7
  37. Lavery L L, Whiting G L and Arias A C 2011 All ink-jet printed polyfluorene photosensor for high illuminance detection Org. Electron. 12 682-5
  38. Lochner C M, Khan Y, Pierre A and Arias A C 2014 All- organic optoelectronic sensor for pulse oximetry Nat. Commun. 5 5745
  39. Armin A, Hambsch M, Kim I K, Burn P L, Meredith P and Namdas E B 2014 Thick junction broadband organic photodiodes Laser Photon. Rev. 8 924-32
  40. Guo F et al 2012 A nanocomposite ultraviolet photodetector based on interfacial trap-controlled charge injection Nat. Nano. 7 798-802
  41. Falco A, Zaidi A M, Lugli P and Abdellah A 2015 Spray deposition of polyethylenimine thin films for the fabrication of fully-sprayed organic photodiodes Org. Electron. 23 186-92
  42. Hamilton M C, Martin S and Kanicki J 2004 Thin-film organic polymer phototransistors IEEE Trans. Electron Devices 51 877-85
  43. Bube R H 1992 Photoelectric Properties of Semiconductors (Cambridge: Cambridge University Press) ISBN: 0521406811
  44. Xu H et al 2013 A high-sensitivity near-infrared phototransistor based on an organic bulk heterojunction Nanoscale 5 11850-5
  45. Takanashi Y, Takahata K and Muramoto Y 1999 Characteristics of InAlAs/InGaAs high-electron-mobility transistors under illumination with modulated light IEEE Trans. Electron Devices 46 2271-7
  46. Zhang L et al 2013 Large-area, flexible imaging arrays constructed by light-charge organic memories Sci Rep-Uk 3 1080
  47. Yuan Y and Huang J 2016 Ultrahigh gain, low noise, ultraviolet photodetectors with highly aligned organic crystals Adv. Opt. Mater. 4 264-70
  48. Yan F, Li J and Mok S M 2009 Highly photosensitive thin film transistors based on a composite of poly(3-hexylthiophene) and titania nanoparticles J. Appl. Phys. 106 074501
  49. Li L et al 2015 Achieving EQE of 16,700% in P3HT:PC71BM based photodetectors by trap-assisted photomultiplication Sci. Rep. 5 9181
  50. Dong R et al 2015 High-gain and low-driving-voltage photodetectors based on organolead triiodide perovskites Adv. Mater. 27 1912-8
  51. Hammond W T and Xue J 2010 Organic heterojunction photodiodes exhibiting low voltage, imaging-speed photocurrent gain Appl. Phys. Lett. 97 073302
  52. Dong R et al 2014 An ultraviolet-to-NIR broad spectral nanocomposite photodetector with gain Adv. Opt. Mater. 2 549-54
  53. Shen L, Fang Y, Wei H, Yuan Y and Huang J 2016 A highly sensitive narrowband nanocomposite photodetector with gain Adv. Mater. 28 2043-8
  54. Han H et al 2015 Broadband all-polymer phototransistors with nanostructured bulk heterojunction layers of NIR- sensing n-type and visible light-sensing p-type Polym. Sci. Rep.-Uk 5 16547
  55. Li F et al 2015 Ambipolar solution-processed hybrid perovskite phototransistors Nat. Commun. 6 8238
  56. Rim Y S et al 2015 Ultrahigh and broad spectral photodetectivity of an organic-inorganic hybrid phototransistor for flexible electronics Adv. Mater. 27 6885-91
  57. Kim M et al 2014 Flexible organic phototransistors based on a combination of printing methods Org. Electron. 15 2677-84
  58. Fukuda K et al 2015 Reverse-offset printing optimized for scalable organic thin-film transistors with submicrometer channel lengths Adv. Electron. Mater. 1 n/a-n/a
  59. Wang H et al 2014 Inkjet printing short-channel polymer transistors with high-performance and ultrahigh photoresponsivity Adv. Mater. 26 4683-9
  60. Granstrom M, Petritsch K, Arias A C, Lux A, Andersson M R and Friend R H 1998 Laminated fabrication of polymeric photovoltaic diodes Nature 395 257-60
  61. Yu G, Wang J, McElvain J and Heeger A J 1998 Large-area, full-color image sensors made with semiconducting polymers Adv. Mater. 10 1431-4
  62. Xu X, Davanco M, Qi X and Forrest S 2008 Direct transfer patterning on three dimensionally deformed surfaces at micrometer resolutions and its application to hemispherical focal plane detector arrays Org. Electron. 9 1122-7
  63. Saito H, Hoshino K, Matsumoto K and Shimoyama I (ed) 2005 Compound eye shaped flexible organic image sensor with a tunable visual field 2005 18th IEEE Int. Conf. on IEEE Micro Electro Mechanical Systems, 2005 MEMS (Piscataway, NJ: IEEE) (doi:10.1109/MEMSYS.2005.1453876)
  64. Chu Y et al 2016 Photosensitive and flexible organic field- effect transistors based on interface trapping effect and their application in 2D imaging array Adv. Sci. 3 1500435
  65. Liu X, Lee E K, Kim D Y, Yu H and Oh J H 2016 Flexible organic phototransistor array with enhanced responsivity via metal-ligand charge transfer ACS Appl. Mater. Interfaces 8 7291-9
  66. Nau S, Wolf C, Sax S and List-Kratochvil E J 2015 Organic non-volatile resistive photo-switches for flexible image detector arrays Adv. Mater. 27 1048-52
  67. Deng W et al 2016 Aligned single-crystalline perovskite microwire arrays for high-performance flexible image sensors with long-term stability Adv. Mater. 28 2201-8
  68. James S, Arujo P and Carlos A 1989 Ferroelectric memories Science 246 1400-5
  69. Chin H-A et al 2016 A flexible barium strontium titanate photodetector array Extreme Mech. Lett. (doi:10.1016/j. eml.2016.02.015)
  70. Liu X et al 2014 Scalable integration of indium zinc oxide/ photosensitive-nanowire composite thin-film transistors for transparent multicolor photodetectors array Adv. Mater. 26 2919-24
  71. Street R, Chabinyc M, Endicott F and Ong B 2006 Extended time bias stress effects in polymer transistors J. Appl. Phys. 100 114518
  72. Someya T et al 2005 Integration of organic FETs with organic photodiodes for a large area, flexible, and lightweight sheet image scanners IEEE Trans. Electron Devices 52 2502-11
  73. Takahashi T et al 2013 Carbon nanotube active-matrix backplanes for mechanically flexible visible light and x-ray imagers Nano Lett. 13 5425-30
  74. Jeong S W, Jeong J W, Chang S, Kang S Y, Cho K I and Ju B K 2010 The vertically stacked organic sensor-transistor on a flexible substrate Appl. Phys. Lett. 97 253309
  75. Nausieda I, Kyungbum R, Kymissis I, Akinwande A, Bulovic V and Sodini C G 2008 An organic active-matrix imager IEEE Trans. Electron Devices 55 527-32
  76. Malinowski P E et al 2013 Fully organic integrated arrays on flexible substrates for x-ray imaging Conf. Proc. Int. Image Sensor Society (IISW) (Snowbird, June 13th 2013)
  77. Renshaw C K, Xu X and Forrest S R 2010 A monolithically integrated organic photodetector and thin film transistor Org. Electron. 11 175-8
  78. Tong X and Forrest S 2011 An integrated organic passive pixel sensor Org. Electron. 12 1822-5
  79. Gelinck G H et al 2013 X-ray imager using solution processed organic transistor arrays and bulk heterojunction photodiodes on thin, flexible plastic substrate Org. Electron. 14 2602-9
  80. Baierl D et al 2012 A hybrid CMOS-imager with a solution- processable polymer as photoactive layer Nat. Commun. 3 1175
  81. Baierl D (ed) 2011 Towards a hybrid CMOS-imager with organic semiconductors as photoactive layer 2011 7th Conf. on Ph D Research in Microelectronics and Electronics (PRIME) (Piscataway, NJ: IEEE) (doi:10.1109/PRIME.2011.5966224)
  82. Jang J, Kitsomboonloha R, Swisher S L, Park E S, Kang H and Subramanian V 2013 Transparent high-performance thin film transistors from solution-processed SnO 2 /ZrO 2 gel-like precursors Adv. Mater. 25 1042-7
  83. Sakai T et al 2011 A 128 × 96 pixel, 50 μm pixel pitch transparent readout circuit using amorphous In-Ga-Zn-O thin-film transistor array with indium-tin oxide electrodes for an organic image sensor Japan. J. Appl. Phys. 51 010202
  84. Scheideler W J, Jang J, Karim M A U, Kitsomboonloha R, Zeumault A and Subramanian V 2015 Gravure-printed sol- gels on flexible glass: a scalable route to additively patterned transparent conductors ACS Appl. Mater. Interfaces 7 12679-87
  85. Milvich J et al 2015 Flexible low-voltage organic phototransistors based on air-stable dinaphtho [2, 3-b: 2′, 3′- f] thieno [3, 2-b] thiophene (DNTT) Org. Electron. 20 63-8
  86. Fan Z, Ho J C, Jacobson Z A, Razavi H and Javey A 2008 Large-scale, heterogeneous integration of nanowire arrays for image sensor circuitry Proc. Natl Acad. Sci. 105 11066-70
  87. Wang H, Liu H, Zhao Q, Cheng C, Hu W and Liu Y 2015 Three-component integrated ultrathin organic photosensors for plastic optoelectronics Adv. Mater. 28 624-30
  88. Kim J et al 2016 Ultrahigh detective heterogeneous photosensor arrays with in-pixel signal boosting capability for large-area and skin-compatible electronics Adv. Mater. 28 3078-86
  89. Kim J, Kim K, Kim Y and Park S 2016 Monolithic integration and design of solution-processed metal-oxide circuitry in organic photosensor arrays IEEE Electron Device Lett. 37 671-3
  90. Nishimura K (ed) 2016 An over 120 dB simultaneous-capture wide-dynamic-range 1.6e? Ultra-low-reset-noise organic- photoconductive-film CMOS image sensor IEEE International Solid-State Circuits Conference (ISSCC) (31 January-4 February 2016) (doi:10.1109/ ISSCC.2016.7417931)
  91. Tedde S, Zaus E, Fürst J, Henseler D and Lugli P 2007 Active pixel concept combined with organic photodiode for imaging devices IEEE Electron Device Lett. 28 893-5
  92. Kang H, Jagannathan L and Subramanian V 2011 Measurement, analysis, and modeling of 1/f noise in pentacene thin film transistors Appl. Phys. Lett. 99 062106
  93. Fan Z Y et al 2009 Toward the development of printable nanowire electronics and sensors Adv. Mater. 21 3730-43
  94. Shishido S (ed) 2016 210ke? Saturation signal 3μm-pixel variable-sensitivity global-shutter organic photoconductive image sensor for motion capture IEEE Int. Solid-State Circuits Conf. (ISSCC) (31 January-4 February 2016) (doi:10.1109/ ISSCC.2016.7417932)
  95. Konstantatos G et al 2006 Ultrasensitive solution-cast quantum dot photodetectors Nature 442 180-3
  96. Lim S-J et al 2015 Organic-on-silicon complementary metal- oxide-semiconductor colour image sensors Sci. Rep.-Uk 5 7708
  97. Ko H C et al 2008 A hemispherical electronic eye camera based on compressible silicon optoelectronics Nature 454 748-53
  98. Jung I et al 2011 Dynamically tunable hemispherical electronic eye camera system with adjustable zoom capability Proc. Natl Acad. Sci. 108 1788-93
  99. Brückner A, Duparré J, Leitel R, Dannberg P, Bräuer A and Tünnermann A 2010 Thin wafer-level camera lenses inspired by insect compound eyes Opt. Express 18 24379-94
  100. Brückner A, Leitel R, Oberdörster A, Dannberg P, Wippermann F and Bräuer A 2011 Multi-aperture optics for wafer-level cameras J. Micro/Nanolithogr. MEMS MOEMS 10 043010
  101. Brückner A, Oberdörster A, Dunkel J, Reimann A, Müller M and Wippermann F (ed) 2014 Ultra-thin wafer- level camera with 720p resolution using micro-optics SPIE Optical Engineering + Applications (International Society for Optics and Photonics) (doi:10.1117/12.2061006)
  102. Sun H, Deng S, Cui X and Lu M 2014 Fabrication of microlens arrays with varied focal lengths on curved surfaces using an electrostatic deformed template J. Micromech. Microeng. 24 065008
  103. Song Y M et al 2013 Digital cameras with designs inspired by the arthropod eye Nature 497 95-9
  104. Peng B, Ren X, Wang Z, Wang X, Roberts R C and Chan P K L 2014 High performance organic transistor active-matrix driver developed on paper substrate Sci. Rep.-Uk 4 6430
  105. Fukuda K et al 2014 Fully-printed high-performance organic thin-film transistors and circuitry on one-micron-thick polymer films Nat. Commun. 5 4147
  106. Maiellaro G et al 2013 High-gain operational transconductance amplifiers in a printed complementary organic TFT technology on flexible foil IEEE Trans. Circuits Syst. I 60 3117-25
  107. Kang H et al 2014 Megahertz-class printed high mobility organic thin-film transistors and inverters on plastic using attoliter-scale high-speed gravure-printed sub-5 μm gate electrodes Org. Electron. 15 3639-47
  108. Kitsomboonloha R, Kang H, Grau G, Scheideler W and Subramanian V 2015 MHz-range fully printed high- performance thin-film transistors by using high-resolution gravure-printed lines Adv. Electron. Mater. 1 1500155
  109. Watson C P and Taylor D M 2011 Demonstration of interfacial charge transfer in an organic charge injection device Appl. Phys. Lett. 99 223304
  110. Pierre A, Sadeghi M, Payne M M, Facchetti A, Anthony J E and Arias A C 2014 All-printed flexible organic transistors enabled by surface tension-guided blade coating Adv. Mater. 26 5722-7

Related papers

Hole-Transporting Transistors and Circuits Based on the Transparent Inorganic Semiconductor Copper(I) Thiocyanate (CuSCN) Processed from Solution at Room Temperature
Jinhua Li

The wide bandgap and highly transparent inorganic compound copper(I) thiocyanate (CuSCN) is used for the first time to fabricate p-type thin-film transistors processed from solution at room temperature. By combining CuSCN with the high-k relaxor ferroelectric polymeric dielectric P(VDF-TrFE-CFE), we demonstrate low-voltage transistors with hole mobilities on the order of 0.1 cm2 V−1 s−1. By integrating two CuSCN transistors, unipolar logic NOT gates are also demonstrated.

View PDFchevron_right
Band-Tail Transport of CuSCN: Origin of Hole Extraction Enhancement in Organic Photovoltaics
Minju Kim

The Journal of Physical Chemistry Letters, 2016

Copper thiocyanate (CuSCN) is known as a promising hole transport layer in organic photovoltaics (OPVs) due to its good hole conduction and exciton blocking abilities with high transparency. Despite its successful device applications, the origin of its hole extraction enhancement in OPVs has not yet been understood. Here, we investigated the electronic structure of CuSCN and the energy level alignment at the poly(3-hexylthiophene-2,5-dinyl) (P3HT)/CuSCN/ITO interfaces using ultraviolet photoelectron spectroscopy. The band-tail states of CuSCN close to the Fermi level (E F) were observed at 0.25 eV below the E F , leading to good hole transport. The CuSCN interlayer significantly reduces the hole transport barrier between ITO and P3HT due to its high work function and band-tail states. The barrier reduction leads to enhanced current density-voltage characteristics of hole-dominated devices. These results provide the origin of hole-extraction enhancement by CuSCN and insights for further application.

View PDFchevron_right
ELECTROCHEMICAL STUDY OF CuSCN INORGANIC HOLE-TRANSPORT MATERIAL FOR SOLAR CELLS PREPARED BY ELECTRODEPOSITION FROM AQUEOUS SOLUTION
Věra Mansfeldová

NANOCON Conference Proeedings

A comparative study is reported for electrodeposited copper(I) thiocyanate layers (ca. 500 nm) on two types of conductive/semiconductive substrates; i) carbon (boron-doped diamond_BDD, glass-like carbon_GC), and ii) carbon-free F-doped SnO2 conducting glass (FTO). SEM and Raman evidence that electrodeposition from aqueous solution results in homogenous CuSCN layers with dominant thiocyanate ion bounded to copper through its Send (Cu−SCN bonding), as in spin-coated CuSCN layers. Electrochemical impedance spectroscopy (EIS) confirms the p-type semiconductivity of layers with a flatband potential from 0.1 to 0.18 V vs. Ag/AgCl depending on the substrate type, and the acceptor concentration (NA) of  5 x 10 20 cm-3 in all cases. The flatband potentials determined from Mott-Schottky plots (EIS) are in good agreement with the Kelvin probe measurements. The blocking quality of CuSCN layers was tested using Ru(NH3)6 3+/2+ redox probe. CuSCN deposited on BDD substrate exhibits better blocking properties compared to CuSCN deposited on FTO.

View PDFchevron_right
Insights into CuSCN nanowire electrodeposition on flexible substrates
Raul Salazar

Electrochimica Acta, 2013

After the first report describing copper thiocyanate (CuSCN) nanowires (NWs) electrochemical deposition from an aqueous electrolyte at room temperature [1], the present study provides additional information on the effect of complexing agent and pH on their formation. The CuSCN electrodeposition from an aqueous solution is a two-step reaction, where in the first step Cu 2+ is reduced to Cu + , and in the second step Cu + chemically precipitates with SCN − to form CuSCN. In this study, CuSCN NWs are electrodeposited either potentiostatically or galvanostatically on flexible polyethylene terephthalate (PET) substrates covered with a transparent conductive oxide. It is shown that the nature of the Cu 2+ chelating agent (diamino-tetraacetic acid compounds) and the pH value (between 1 and 2) of the electrolyte are the main parameters responsible for the CuSCN nanowire formation. The concentration limits of the Cu 2+ chelating agent, Cu 2+ and SCN − ions in the electrolyte are established to precise the region where CuSCN NWs could be grown. The CuSCN nanowire diameter and density could be tailored by the applied potential and SCN − concentration in the electrolyte. The possibility to deposit at room temperature CuSCN of good crystalline quality on flexible substrates is very promising and could further contribute to the decrease of the optoelectronic and photovoltaic device cost.

View PDFchevron_right
Doping CuSCN films for enhancement of conductivity: Application in dye-sensitized solid-state solar cells
Kirthi Tennakone

Solar Energy Materials and Solar Cells, 2005

Construction of dye-sensitized solid-state solar cells requires high band-gap (therefore, transparent) hole collectors which can be deposited on a dye-coated nanocrystalline semiconductor surface without denaturing the dye. Copper (I) thiocyanate (CuSCN) is an important p-type semiconductor satisfying the above requirements. However, the conductivity of this material, which depends on excess SCN, is not sufficiently high and polymerization of SCN prevents incorporation of sufficient amount of excess SCN during the process of synthesis of CuSCN. We have found that the conductivity of solid CuSCN can be increased by exposure to halogen gases which generate SCN or to a solution of (SCN) 2 in CCl 4 . The latter method is suitable for doping of CuSCN films in dye-sensitized solid-state solar cells.

View PDFchevron_right

Related topics

  • Materials Science
  • Computer Vision
  • Flexible Printed Electronics

    • Cited by

    Ultraflexible Integrated Organic Electronics for Ultrasensitive Photodetection
    Haoyang WANG

    Advanced Materials Technologies

    View PDFchevron_right
    Organic and Amorphous-Metal-Oxide Flexible Analogue Electronics
    Sahel Abdinia

    This publication is in copyright. Subject to statutory exception and to the provisions of relevant collective licensing agreements, no reproduction of any part may take place without the written permission of Cambridge University Press.

    View PDFchevron_right
    Charge-integrating organic heterojunction phototransistors for wide-dynamic-range image sensors
    Adrien Pierre

    Nature Photonics

    Solution-processed phototransistors can substantially advance the performance of image sensors. Phototransistors exhibit large photoconductive gain and a sublinear responsivity to irradiance, which enables a logarithmic sensing of irradiance that is akin to the human eye and has a wider dynamic range than photodiode-based image sensors. Here, we present a novel solution-processed phototransistor composed of a heterostructure between a high-mobility organic semiconductor and an organic bulk heterojunction. The device efficiently integrates photogenerated charge during the period of a video frame then quickly discharges it, which significantly increases the signal-to-noise ratio compared with sampling photocurrent during readout. Phototransistor-based image sensors processed without photolithography on plastic substrates integrate charge with external quantum efficiencies above 100% at 100 frames per second. In addition, the sublinear responsivity to irradiance of these devices enables a wide dynamic range of 103 dB at 30 frames per second, which is competitive with state-of-the-art image sensors.

    View PDFchevron_right
    Bioelectronic devices for light-based diagnostics and therapies
    Weni Sritandi

    Biophysics Reviews

    Light has broad applications in medicine as a tool for diagnosis and therapy. Recent advances in optical technology and bioelectronics have opened opportunities for wearable, ingestible, and implantable devices that use light to continuously monitor health and precisely treat diseases. In this review, we discuss recent progress in the development and application of light-based bioelectronic devices. We summarize the key features of the technologies underlying these devices, including light sources, light detectors, energy storage and harvesting, and wireless power and communications. We investigate the current state of bioelectronic devices for the continuous measurement of health and on-demand delivery of therapy. Finally, we highlight major challenges and opportunities associated with light-based bioelectronic devices and discuss their promise for enabling digital forms of health care.

    View PDFchevron_right
    580 California St., Suite 400
    San Francisco, CA, 94104
    © 2025 Academia. All rights reserved