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Improvement of Ga distribution with Sb incorporation for two-step low-temperature processing of CIGSe thin film solar cells
摘要： In this study, the application of Sb incorporation for low-temperature (≤ 450 °C) processing of Cu(In,Ga)Se2 (CIGSe) solar cells is explored. At low reaction temperature, most Ga remains at the back of the ?lm adjacent to the Mo back contact. We observed that the incorporated Sb enhanced grain size and improved device performance compared with similarly processed CIGSe ?lms made without Sb. From the energy-dispersive spectroscopy analysis and secondary ion mass spectrometry results, it was determined that elemental Ga accumulation at the back of the reacted ?lm after the two-step selenization process was signi?cantly alleviated owing to Sb incorporation. Signi?cant Sb-induced grain size enhancement was con?rmed using cross-sectional scanning electron microscopy. The electronic and optical properties of the Sb incorporated CIGSe ?lms were examined with admittance spectroscopy and ?uorescence lifetime imaging techniques.
关键词： Ga distribution,Thin ?lm solar cell,Sb incorporation,Low temperature process
更新于2025-11-14 17:28:48
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Light-illumination stability of amorphous InGaZnO thin film transistors in oxygen and moisture ambience
摘要： The light-illumination stability of amorphous InGaZnO Thin Film Transistors (a-IGZO TFTs) in oxygen and moisture ambience was in-depth characterized by both current-voltage (I-V) and capacitance-voltage (C-V) measurements. With the illuminated light wavelength decreasing, both I-V and C-V curves shifted negatively. When the ambient oxygen content or moisture level increased, the a-IGZO TFTs exhibited more stable properties under light illumination. A qualitative model was proposed to explain the related physical mechanism. The higher oxygen content or moisture level bene?ted the light-illumination-induced oxygen adsorption at back channels of a-IGZO TFTs and prevented the formation of oxygen vacancies (VO) in channel layers; the VO variation with the light illumination became more di?cult and hence led to better light-illumination stability of the corresponding TFT devices.
关键词： Thin ?lm transistor,Light-illumination stability,Amorphous InGaZnO,Ambient gases
更新于2025-09-23 15:23:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - 50mW Average Power Gas-Plasma THz Generation Driven by a Fiber Laser
摘要： Amorphous indium–gallium–zinc oxide (a-IGZO) thin-?lm transistor nonvolatile memory devices with an IGZO charge storage layer were evaluated for the ?rst time for multi-level cell memory applications. The pristine device was de?ned as the original state (OS), which can be switched to the programmed state (PS) after a positive gate voltage pulse (for example, 12 V for 10 ms), and to the erased state (ES) after a negative gate voltage pulse (for example, ?15 V for 10 ms). The writing mechanism was attributed to Fowler–Nordheim tunneling of electrons from the channel to the charge storage layer under a positive gate bias and inverse tunneling under a negative gate bias. The devices demonstrated superior electrical programmable and erasable characteristics. A memory window of 2.4 V between OS and PS was maintained after 100 programming/erasing cycles, and a memory window of 2.66 V between OS and ES as well. The memory windows relative to OS are equal to 1.91 and 1.30 V for PS and ES, respectively, for a retention time of 105 s.
关键词： nonvolatile memory,thin-?lm transistor,multi-level cell,In-Ga-Zn-O
更新于2025-09-23 15:21:01
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Minimizing Defect States in Lead Halide Perovskite Solar Cell Materials
摘要： In order to reach the theoretical e?ciency limits of lead-based metal halide perovskite solar cells, the voltage should be enhanced because it su?ers from non-radiative recombination. Perovskite materials contain intrinsic defects that can act as Shockley–Read–Hall recombination centers. Several experimental and computational studies have characterized such defect states within the band gap. We give a systematic overview of compositional engineering by distinguishing the di?erent defect-reducing mechanisms. Doping e?ects are divided into in?uences on: (1) crystallization; (2) lattice properties. Incorporation of dopant in?uences the lattice properties by: (a) lattice strain relaxation; (b) chemical bonding enhancement; (c) band gap tuning. The intrinsic lattice strain in undoped perovskite was shown to induce vacancy formation. The incorporation of smaller ions, such as Cl, F and Cd, increases the energy for vacancy formation. Zn doping is reported to induce strain relaxation but also to enhance the chemical bonding. The combination of computational studies using (DFT) calculations quantifying and qualifying the defect-reducing propensities of di?erent dopants with experimental studies is essential for a deeper understanding and unraveling insights, such as the dynamics of iodine vacancies and the photochemistry of the iodine interstitials, and can eventually lead to a more rational approach in the search for optimal photovoltaic materials.
关键词： semiconductor,solar energy,photovoltaics,doping,thin ?lm materials,voltage loss,stabilization,optimization,charge generation,light harvesting
更新于2025-09-23 15:21:01
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Strongly Enhancing Photocatalytic Activity of TiO2 Thin Films by Multi-Heterojunction Technique
摘要： The photocatalysts of immobilized TiO2 ?lm suffer from high carrier recombination loss when compared to its powder form. Although the TiO2 with rutile-anatase mixed phases has higher carrier separation ef?ciency than those with pure anatase or rutile phase, the single junction of anatase/rutile cannot avoid the recombination of separated carriers at the interface. In this study, we propose a TiO2/SnO2/Ni multi-heterojunction structure which incorporates both Schottky contact and staggered band alignment to reduce the carrier recombination loss. The low carrier recombination rate of TiO2 ?lm in TiO2/SnO2/Ni multi-heterojunction structure was veri?ed by its low photoluminescence intensity. The faster degradation of methylene blue for TiO2/SnO2/Ni multi-junctions than for the other fabricated structures, which means that the TiO2 ?lms grown on the SnO2/Ni/Ti coated glass have a much higher photocatalytic activity than those grown on the blank glass, SnO2-coated and Ni/Ti-coated glasses, demonstrated its higher performance of photogenerated carrier separation.
关键词： titanium dioxide,multijunction,thin ?lm,photocatalysis,functional coatings
更新于2025-09-23 15:21:01
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Superior ferroelectric photovoltaic properties in Fe -modified (Pb,La) (Zr,Ti)O3 thin film by improving the remnant polarization and reducing the band gap
摘要： In order to develop ferroelectric photovoltaic devices with high power conversion e?ciency, ferroelectric materials must have simultaneously large remnant polarization and narrow band gap so as to e?ciently separate photo-generated carriers and absorb more sunlight. Based on this idea, in this report, we introduce Fe3+ into Pb0·93La0·07(Zr0·6Ti0.4)0.9825O3 ferroelectric thin ?lm to increase the remnant polarization and decrease the band gap of the thin ?lm. In doing so, we prepare Fe3+ doping Pb0·93La0·07(Zr0·6Ti0.4)0.9825O3 thin-?lm based photovoltaic devices. The experimental results indicate that with increasing the Fe3+ amount, the remnant polarization of the ?lm ?rst improves to the maximum value of 50 μC/cm2 at the 4.8 mol% Fe3+ content and then reduces gradually, while the band gap continuously decreases. In addition, at a negative poling voltage, the device exhibits larger short-circuit current and open-circuit voltage in comparison with those obtained at the positive poling voltage, which is attributed to the depolarization electric ?eld originating from the remnant polarization of ferroelectric thin ?lms in the same direction as the built-in electric ?eld caused by the Schottky barrier. In this report, the most superior photovoltaic performances with the open-circuit voltage of as large as ?0.55 V and short-circuit current of as high as 0.4 μA/cm2 are obtained in the device with 4.8 mol% Fe3+ amount and at ?5 V poling voltage. This is on account of the improved sunlight absorbing properties and photo-generated carriers separation ability of the device. This work provides a novel idea for designing and preparing ferroelectric photovoltaic devices with high power conversion e?ciency.
关键词： Fe3+ doping,Photovoltaic properties,Band gap,Remnant polarization,Ferroelectric thin ?lm
更新于2025-09-23 15:21:01
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[ACM Press the International Conference - San Diego, California (2018.11.05-2018.11.08)] Proceedings of the International Conference on Computer-Aided Design - ICCAD '18 - Strain-aware performance evaluation and correction for OTFT-based flexible displays
摘要： Organic thin-?lm transistors (OTFTs) are widely used in ?exible circuits, such as ?exible displays, sensor arrays, and radio frequency identi?cation cards (RFIDs), because these technologies offer features such as better ?exibility, lower cost, and easy manufacturability using low-temperature fabrication process. This paper develops a procedure that evaluates the performance of ?exible displays. Due to their very nature, ?exible displays experience signi?cant mechanical strain/stress in the ?eld due to the deformation caused during daily use. These deformations can impact device and circuit performance, potentially causing a loss in functionality. This paper ?rst models the effects of extrinsic strain due to two fundamental deformations modes, bending and twisting. Next, this strain is translated to variations in device mobility, after which analytical models for error analysis in the ?exible display are derived based on the rendered image values in each pixel of the display. Finally, two error correction approaches for ?exible displays are proposed, based on voltage compensation and ?exible clocking.
关键词： Organic thin-?lm transistors (OTFTs),performance evaluation,error correction,strain modeling,?exible displays
更新于2025-09-23 15:21:01
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Cd-free Cu(InGa)Se2 solar cells with eco-friendly a-Si buffer layers
摘要： CdS, In2S3 and ZnO-based materials are typically adopted as bu?er layers in high e?ciency CIGS solar cells. However, the drawbacks involved toxicity, complicated synthesis process and environmental damage of aforementioned materials would someday limit the development themselves. Here, for the ?rst time, eco-friendly and low-cost a-Si thin ?lms prepared by e-beam evaporation were used as bu?er layers in CIGS solar cells. Thickness of a-Si ?lms was changed to optimize the performance of CIGS solar cells through investigating their optical, structural and electrical properties. It revealed that the conduction band alignment of CIGS and a-Si is a favorable spike and a 60 nm a-Si ?lm is optimal for CIGS/a-Si interface properties. Following the SCAPS simulation, bandgaps and conduction band energy level of CIGS ?lms were facilely modulated through altering the Ga/(Ga + In) ratios. The conversion e?ciency of solar cell with modi?ed CIGS ?lm was relatively improved by over 30% compared to the pristine one. The present work provides a new and eco-friendly strategy for fabrication of CIGS solar cells and expands the application of a-Si thin ?lms as bu?er layers for solar cells.
关键词： CIGS thin ?lm,Cd-free solar cell,a-Si thin ?lm,SCAPS simulation
更新于2025-09-23 15:19:57
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Nanomolded buried light-scattering (BLiS) back-reflectors using dielectric nanoparticles for light harvesting in thin-film silicon solar cells
摘要： The article presents a nanoparticle-based buried light-scattering (BLiS) back-re?ector design realized through a simpli?ed nanofabrication technique for the purpose of light-management in solar cells. The BLiS structure consists of a ?at silver back-re?ector with an overlying light-scattering bilayer which is made of a TiO2 dielectric nanoparticles layer with micron-sized inverted pyramidal cavities, buried under a ?at-topped silicon nanoparticles layer. The optical properties of this BLiS back-re?ector show high broadband and wide angular distribution of diffuse light-scattering. The ef?cient light-scattering by the buried inverted pyramid back-re?ector is shown to effectively improve the short-circuit-current density and ef?ciency of the overlying n-i-p amorphous silicon solar cells up to 14% and 17.5%, respectively, compared to the reference ?at solar cells. A layer of TiO2 nanoparticles with exposed inverted pyramid microstructures shows equivalent light scattering but poor ?ll factors in the solar cells, indicating that the overlying smooth growth interface in the BLiS back-re?ector helps to maintain a good ?ll factor. The study demonstrates the advantage of spatial separation of the light-trapping and the semiconductor growth layers in the photovoltaic back-re?ector without sacri?cing the optical bene?t.
关键词： light management,nanomolding,inverted pyramids,thin-?lm solar cells,nanoparticles,photovoltaics
更新于2025-09-23 15:19:57
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SrCl <sub/>2</sub> an environment friendly alternate to CdCl <sub/>2</sub> treatment for CdTe thin films solar cell application
摘要： The CdCl2 treatment is a an important step for CdTe absorber based solar cell, however CdCl2 is less abundant, toxic and extremely environment unfriendly. We propose strontium chloride SrCl2 as a possible environment friendly replacement which is non-toxic, abundant and provide comparable ef?ciency to thin ?lm solar cell. In this work the CdTe thin ?lm was prepared by closed space sublimation (CSS) technique, while SrCl2 was further coated by a spin coater and ?nally annealed at 200 °C. The structural properties including particle size, dislocation density and strain were determined. The structural analysis reveals that the ?lms are crystalline, cubic zinc-blende structure with preferred orientation of (111) plane. Presence of SrCl2 layer causes increase in the intensities for other orientations of (220) and (311), showing material loses in the preferred orientation of (111) making it polycrystalline. Surface morphology observed by SEM shows improved uniformity with fewer defects after SrCl2 treatment. Band gap and other optical properties were determined using spectroscopic ellipsometry. Optical band gap is found in the range 1.6 eV to 1.4 eV and observed to decrease with the increasing SrCl2 content. The electrical conductivity is observed increasing with the addition of second layer. We report that the SrCl2 coated thin ?lms are ef?cient, comparable and environmental friendly replacement for the CdCl2 coated CdTe thin ?lms.
关键词： thin ?lm solar cell,CdTe,CdCl2 coating,SrCl2 coating
更新于2025-09-23 15:19:57