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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Evaluating the Electricity Production and Energy Saving from Transparent Photovoltaics for Windows in Commercial Buildings
摘要： A pentacene (C22H14)-based high-voltage organic thin-film transistor (HVOTFT) was demonstrated on both a rigid and a flexible substrate. The HVOTFT showed minimal degradation of the current–voltage (I–V ) characteristics under flexure. Consistent with the previous reports on amorphous silicon (a-Si) TFTs, the offset drain/source structure enabled high-voltage operation, allowing for the HVOTFT to switch very large drain-to-source voltages (VDS > 300 V) with a relatively lower controlling voltage (0 V < VG < 20 V). The HVOTFT was evaluated with three different gate insulators to assess how the dielectric constant and interface states influence device performance. Due to the high electric field generated in the device, the HVOTFT suffered from impeded charge injection into the gated semiconductor channel, similar to that reported in a-Si-based high-voltage TFTs, as well as from a nonsaturating I–V characteristic behavior similar to the short-channel effects found in FETs. A field plate was implemented to improve charge injection into the gated semiconductor channel. Output characteristics of the HVOTFT were numerically corrected to demonstrate that the device I–V can be modeled with the existing Si-based FET models.
关键词： Flexible substrates,high-κ gate dielectrics,organic thin-film transistors (HVTFTs),high-voltage semiconductors
更新于2025-09-19 17:13:59
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High-Performance Ambient-Condition-Processed Polymer Solar Cells and Organic Thin-Film Transistors
摘要： Large-scale commercial synthesis of bulk-heterojunction (BHJ) solar cell materials is very challenging and both time and energy consuming. Synthesis of π-conjugated polymers (CPs) with uniform batch-to-batch molecular weight and low dispersity is a key requirement for better reproducibility of high-efficiency polymer solar cells. Herein, a conjugated polymer (CP) PTB7-Th, well known for its high performance, has been synthesized with high molecular weight and low dispersity in a closed microwave reactor. The microwave reaction procedure is known to be more controlled and consumes less energy. The precursors were strategically reacted for different reaction time durations to obtain the optimum molecular weight. All different CPs were well characterized using 1H NMR, gel permeation chromatography (GPC), UV?vis, photoluminescence (PL), electron spin resonance (ESR), and Raman spectroscopy, whereas the film morphology was extensively studied via atomic force microscopy (AFM) and grazing incidence X-ray diffraction (GIXRD) techniques. The effect of molecular weight on a conventional BHJ solar cell with PC71BM acceptor was investigated to derive systematic structure?property relationships. The CP obtained after 35 min of reaction time and integrated into BHJ devices under ambient conditions provided the best performance with a power conversion efficiency (PCE) of 8.09%, which was quite similar to the results of CPs synthesized via a thermal route. An enhanced PCE of 8.47% was obtained for the optimized polymer (35 min microwave reaction product) when device fabrication was carried out inside a glovebox. The organic thin-film transistor (OTFT) device with the microwave-synthesized CP displayed better hole mobility (0.137 cm2 V?1 s?1) as compared to that with the thermally synthesized CP. This study also proved that the device stability and reproducibility of the microwave-synthesized CP were much better and more consistent than those of the thermally developed CP.
关键词： microwave reactor,π-conjugated polymers,organic thin-film transistors,polymer solar cells,bulk-heterojunction
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Is Damp Heat Degradation of c-Si Modules Essentially Universal?
摘要： A pentacene (C22H14)-based high-voltage organic thin-film transistor (HVOTFT) was demonstrated on both a rigid and a flexible substrate. The HVOTFT showed minimal degradation of the current–voltage (I–V ) characteristics under flexure. Consistent with the previous reports on amorphous silicon (a-Si) TFTs, the offset drain/source structure enabled high-voltage operation, allowing for the HVOTFT to switch very large drain-to-source voltages (VDS > 300 V) with a relatively lower controlling voltage (0 V < VG < 20 V). The HVOTFT was evaluated with three different gate insulators to assess how the dielectric constant and interface states influence device performance. Due to the high electric field generated in the device, the HVOTFT suffered from impeded charge injection into the gated semiconductor channel, similar to that reported in a-Si-based high-voltage TFTs, as well as from a nonsaturating I–V characteristic behavior similar to the short-channel effects found in FETs. A field plate was implemented to improve charge injection into the gated semiconductor channel. Output characteristics of the HVOTFT were numerically corrected to demonstrate that the device I–V can be modeled with the existing Si-based FET models.
关键词： Flexible substrates,high-κ gate dielectrics,organic thin-film transistors (HVTFTs),high-voltage semiconductors
更新于2025-09-16 10:30:52
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Organic LED based light sensor for detection of ovarian cancer
摘要： Organic devices possess an interdisciplinary facet that can be utilized in the different fields; communication, memory devices, bio-degradable technology and sensor application owing to their robustness, light weight and low power requirements. The proposed work is focused on the development of a sensor application based on the organic LEDs for the diagnosis of ‘Ovarian Cancer’. Two organic LEDs: Multilayered OLED and triple hole block layer OLED are analyzed for utilization as light detector and light source in the sensing device for cancer detection. Multilayered OLED depicts excellent light detection qualities owing to lower electron hole recombination and it is six times better as compared to the triple hole block layer OLED. Therefore, it is used as the detector element in the sensing device. On the other hand, triple hole block layer OLED, is used as light source due to its high luminescence characteristics of 25,285 cd/m2. Further, a dual gate OTFT is used to drive the triple hole block layer OLED, which is utilized as the light source. DG OTFT in dual gate mode is 18% better compared to single gate mode. Thus DG-OTFT in dual gate mode is able to generate 18 volts at the terminals of the triple HBL OLED necessary for its operation. Thereafter, light detection is performed utilizing the OLED. Multilayered OLED depicted excellent light detecting capabilities. It is able to generate a cathode current of 29mA and 13mA at an incident wavelength of 420 and 440 nm, respectively, an essential requirement for present sensor application. Therefore, it presents a possibility to fabricate a portable fully flexible device for the screening and diagnosis of the ovarian cancer.
关键词： Ovarian Cancer,Triple Hole Block Layer (THBL) OLED,Dual Gate-Organic Thin Film Transistor (DG-OTFT),Bio-Medical Sensor,Organic Light Emitting Diode (OLED)
更新于2025-09-11 14:15:04
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Effect of space charge limited current on performance of organic field-effect transistors
摘要： The crucial parameter that determines the performance of a semiconductor material in organic field-effect transistors (OFETs) is the charge carrier mobility. The conventional method of its determination based on Shockley’s equations can lead to incorrect mobility evaluation due to contact effects. Particularly, in the common staggered OFET architecture (top-contact bottom-gate or bottom-contact top-gate), the space-charge limited current (SCLC) effect in the active layer under/above the source and drain contacts decreases the source-drain current. In this work, we model the effect of SCLC under/above the source and drain electrodes on the OFET apparent mobility (i.e., calculated from the device characteristics) and apparent threshold voltage for different active layer thickness and intrinsic mobility anisotropy. For the saturation regime, we derived simple analytical expressions for transfer characteristics and apparent mobility. Our modeling shows that the apparent OFET mobility is more than five times lower than the intrinsic one for the active layer thicker than 100 nm with mobility anisotropy (along vs across the active layer) higher than 100. While the SCLC effect does not change the apparent threshold voltage, it reveals itself as a kink at near zero voltage in the output characteristics. The proposed model gives analytical expressions for the transfer characteristics and apparent mobility as explicit functions of the intrinsic mobility and the device parameters in the saturation regime and as implicit functions in the linear regime. Our findings provide guidelines for accurate evaluation of the intrinsic mobility in OFETs fabricated in the staggered architecture and for further improvement of OFET performance.
关键词： Organic field-effect transistors,Organic thin-film transistors,Space charge limited current,Contact effects,Modeling
更新于2025-09-11 14:15:04
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High performance phototransistors with organic/quantum dot composite materials channels
摘要： Nanomaterials, especially quantum dots, have become one of the most great potential channel transport layer materials in the field of photo detection mainly due to their particular light absorption characteristics. However, there are still many disadvantages such as low carrier transport capability possibly attributable to the discontinuity nature of materials. Therefore, particular phototransistors with pentacene/CdSe@ZnS QDs composite materials channels have been prepared by simply blending and spin-coating 6,13-Bis(triisopropylsilylethynyl)-pentacene (TIPS-pentacene) and QDs solution in weight ratio of 3:1. The particular device architecture with organic/quantum dot composite materials channels effectively combined the high carrier mobility advantage of organic semiconductors with the strong absorption characteristic of quantum dots in specific optical band regions and further overcame the low conductivity shortcomings of pure quantum dot materials. The device with particular pentacene/CdSe@ZnS QDs composite channel exhibited excellent electrical and optical properties with current switch ratio Ion/off of 104, carriers mobility of ~0.161 cm2/V, photosensitivity P of 105, responsivity R of 0.33 mA/W and detectivity D of 1.48 ? 1011 Jones at drain voltage of (cid:0) 35 V and light intensity of 1.6 mW/cm2, respectively, indicating that this composite, as one of the most promising channel transport layer material candidates for photodetector, provides one chance to improve the characteristic of photodetector transistors just by using hybrid channel technology.
关键词： Solution method,Quantum dots,Photodetectors,Composite materials,Organic thin film transistors
更新于2025-09-11 14:15:04
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Thermal and angular dependence of next‐generation photovoltaics under indoor lighting
摘要： Next‐generation photovoltaic technologies such as dye‐sensitized solar cells, organic thin‐film photovoltaics and perovskite solar cells are promising to efficiently harvest ambient light energy. However, more and deeper understanding of their photovoltaic characteristics is essential to create new applications under room light illumination. In this study, for the first time, the difference in temperature coefficients and angular dependence of photovoltaic parameters for the large‐area devices are investigated systematically under the compact fluorescent lamp and light‐emitting diode light. These emerging photovoltaic devices, compared with the single crystalline silicon solar cells, not only have higher open‐circuit voltage (up to approximate 1 V) and better power conversion efficiency (in the range of 9.2% ~ 22.6%) but also exhibit less temperature dependent voltage and output power (< ?0.6% °C?1), as well as broader angular response (over 75 degrees). The state‐of‐the‐art dye‐sensitized and organic thin‐film devices also show advantageously positive temperature coefficients of current, and the latter even has positive thermal dependence of fill factor. These features suggest the next‐generation photovoltaic devices are more favorable than the conventional crystalline silicon solar cells for real‐life indoor applications.
关键词： dye‐sensitized solar cells,indoor lighting,perovskite solar cells,temperature and angular dependent power,organic thin‐film photovoltaics
更新于2025-09-11 14:15:04
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Optical properties of selenium sulfide thin film produced via chemical dropping method
摘要： This paper describes the production of selenium sulfide (SeS2) crystalline thin film on commercial glass substrates, via chemical bath deposition. Transmittance, absorption, dielectric constant and refractive index of the produced films were investigated by UV/VIS Spectrum. It was found that changes occurred on the characteristics of the films and they were determined as a function of selenium sulfide concentration, which varied between 2 × 10?3 and 5 × 10?3 M. The structure of the film was analyzed using FTIR spectrum. The calculated refractive index values fell between 1.5 and 1.6, whereas the transmission ratio of the films was around 80–90%. Moreover, a peak in the reflectance was observed at 320–330 nm for all investigated samples. The highest dielectric constant for the films was obtained at the deposition concentration of 0.005 M. This study is believed to be useful for thin film production.
关键词： Selenium sulfide,Thin film,Chemical dropping,Organic thin film,SeS2 thin films
更新于2025-09-10 09:29:36
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Uniform Insulating Properties of Low-Temperature Curable Gate Dielectric for Organic Thin-Film Transistor Arrays on Plastic Substrate
摘要： Achieving a high-resolution display on a plastic substrate requires a to ensure dimensional stability during fabrication process, including the deposition of gate dielectrics. Evaluation platform to confirm the uniform insulating properties of organic dielectric material prior to actual application to organic thin-film transistor (OTFT) arrays was proposed. This test method enabled verification of the suitability of the low-temperature curable dielectric and chemical resistance during fabrication process. A cross-linked poly(hydroxy imide) (PHI) that can be cured at a low temperature of 130°C exhibited stable insulating properties in a large area that sudden breakdown was not observed in an electric field up to 4 MV/cm. Thiophene-thiazole-based copolymer semiconductor was used as an active layer and inkjet-printed. In all the processes, the temperature of the substrate was kept below 130°C, and 4.8-inch electrophoretic display panels on a polyethylene naphthalate (PEN) substrate with a resolution of 98 dpi was demonstrated.
关键词： Organic thin-film transistors,Organic gate dielectric,Plastic substrates,Low-temperature process,Polymer semiconductor,Flexible displays,Inkjet printing
更新于2025-09-10 09:29:36
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Actuator-Control Circuit Based on OTFTs and Flow-Rate Estimation for an All-Organic Fluid Pump
摘要： In this paper, we report the design of an organic thin-film transistor (OTFT) driver circuit for the actuator of an organic fluid pump, which can be integrated in a portable-size fully-organic artificial lung. Compared to traditional pump designs, lightness, compactness and scalability are achieved by adopting a creative pumping mechanism with a completely organic-material-based system concept. The transportable fluid volume is verified to be flexibly adjustable, enabling on-demand controllability and scalability of the pump’s fluid-flow rate. The simulations, based on an accurate surface-potential OTFT compact model, demonstrate that the necessary driving waveforms can be efficiently generated and adjusted to the actuator requirements. At the actuator-driving-circuit frequency of 0.98 Hz, an all-organic fluid pump with 40 cm length and 0.2 cm height is able to achieve a flow rate of 0.847 L/min, which satisfies the requirements for artificial-lung assist systems to a weakened normal lung.
关键词： organic thin-film transistor,fluid volume,organic actuator,organic circuit,HiSIM-organic model,artificial lung,circuit simulation
更新于2025-09-09 09:28:46