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Effect of annealing on the physical properties of thermally evaporated In2S3 thin films
摘要： The structural, compositional, morphological and optical properties of In2S3 thin films, prepared by thermal evaporation technique and annealed in sulfur ambient at different temperatures have been investigated. The grazing incident X-ray diffraction patterns have indicated polycrystalline form and predominantly cubic structure of annealed In2S3 films. The scanning electron microscopy revealed textured surface with uniformly distributed grains and the grain size increased with increase of annealing temperature. The optical parameters of the films have been determined using conventional transmission and reflection spectra as well as from surface photovoltage measurements.
关键词： Surface photovoltage,Annealing,In2S3 thin films,Structure,Optical band gap
更新于2025-09-23 15:21:21
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A facile room-temperature synthesis of three-dimensional coral-like Ag2S nanostructure with enhanced photocatalytic activity
摘要： Morphology is a crucial factor in determining the chemical, optical, and electrical properties of nanoscale materials. In this work, we utilized a facile room-temperature deposition method to synthesize three-dimensional (3D) coral-like Ag2S nanostructures. The formation mechanism of 3D coral-like Ag2S nanostructures was proposed by tracking the reaction process. In comparison with 0D Ag2S nanoparticles and 1D Ag2S nanowires of similar size, 3D coral-like Ag2S nanostructures exhibit higher pore volume, photocatalytic activity and cyclic stability for degradation of methyl orange (MO). Surface photovoltage measurement, electrochemical impedance spectroscopy, and Mott–Schottky analysis showed that compared to other Ag2S nanostructures, 3D coral-like Ag2S nanostructures have the strongest surface photovoltaic response, longest carrier lifetime, and highest carrier density.
关键词： Carrier lifetime,Surface photovoltage,Ag2S,3D coral-like nanostructure,Photocatalytic activity
更新于2025-09-23 15:21:21
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Electric dipole of InN/InGaN quantum dots and holes and giant surface photovoltage directly measured by Kelvin probe force microscopy
摘要： We directly measure the electric dipole of inn quantum dots (QDs) grown on in-rich inGan layers by Kelvin probe force microscopy. This significantly advances the understanding of the superior catalytic performance of inn/inGan QDs in ion- and biosensing and in photoelectrochemical hydrogen generation by water splitting and the understanding of the important third-generation inGan semiconductor surface in general. the positive surface photovoltage (SpV) gives an outward QD dipole with dipole potential of the order of 150 mV, in agreement with previous calculations. After HCl-etching, to complement the determination of the electric dipole, a giant negative SpV of ?2.4 V, significantly larger than the inGan bandgap energy, is discovered. this giant SpV is assigned to a large inward electric dipole, associated with the appearance of holes, matching the original QD lateral size and density. Such surprising result points towards unique photovoltaic effects and photosensitivity.
关键词： electric dipole,Kelvin probe force microscopy,surface photovoltage,inn/inGan quantum dots,photovoltaic effects
更新于2025-09-23 15:21:01
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Gradient Formation and Charge Carrier Dynamics of CuBiI4 based Perovskite-like Solar Cells
摘要： Designing lead-free inorganic perovskite or perovskite-like structure materials and researching the corresponding photoinduced charge carrier dynamics are always promising due to both the environment and power conversion efficiency considerations. In this work, we intelligently employ bilayer metal Bi/Cu thin film with different atomic ratios as precursor to in-situ fabricate CuBiI4 perovskite-like film with controlled Bi gradient at room temperature. This structure can significantly affect the photoinduced charge carrier dynamic of the resulting products. Next, a series of transient surface photovoltage (TSPV) measurements have been carried out to investigate the photoinduced charge carrier dynamics of such CuBiI4 and CuBiI4: organic hybrid thin films. It reveals that the gradually decreased Bi content from ITO to CuBiI4 can help the photoinduced charge carrier transportation. Finally, a champion PCE of 1.10% has been obtained from an ITO/ CuBiI4: polythieno[3,4-b]-thiophene-co-benzodithiophene (PTB7)/ Au solar cell device. In particular, we find an exact negative correlation of the defined parameter L (the defined value for evaluating the photoinduced charge carrier dynamic in TSPV measurements) with the corresponding PCE of various devices for the first time, which may pave a new way for evaluating the potential photoelectric and photovoltaic performances of new materials without assembly of solar cell devices.
关键词： CuBiI4,solar cell,photoinduced charge carrier dynamics,lead-free inorganic perovskite,transient surface photovoltage
更新于2025-09-23 15:19:57
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Atomic layer deposition of amorphous antimony sulfide (a-Sb <sub/>2</sub> S <sub/>3</sub> ) as semiconductor sensitizer in extremely thin absorber solar cell
摘要： Atomic layer deposition of amorphous antimony sulfide (a-Sb2S3) is demonstrated with an alternating exposure of tris(dimethylamino) antimony (TDMASb) and hydrogen sulfide (H2S) at 150 °C in a custom-built viscous flow reactor. Growth mechanism and deposition chemistry are investigated by in situ quartz crystal microbalance and in situ Fourier Transform Infrared spectroscopy. Reaction hypothesis facilitating the binary reaction is established by quantum mechanical density functional theory calculations that essentially support the experimental findings. The developed material is used as a photon harvester in solar cells under extremely thin absorber configuration, with TiO2 and Spiro-OMeTAD as electron and hole transporting layers, respectively. Investigation of charge injection properties with surface photovoltage spectroscopy reveals low but non-negligible density of interfacial (sensitizer/TiO2) electronic defects. The conventional viscous flow reactor configuration is modified to showerhead-type reactor configuration to achieve better uniformity and conformality of a-Sb2S3 on highly porous TiO2 scaffolds. a-Sb2S3 device performance is optimized to achieve the highest power conversion efficiencies of 0.5% while annealed crystalline c-Sb2S3 device reaches power conversion efficiencies of 1.9% under 1 sun illumination.
关键词： surface photovoltage spectroscopy,extremely thin absorber solar cell,quantum mechanical density functional theory,amorphous antimony sulfide,Atomic layer deposition
更新于2025-09-19 17:13:59
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The Origin of Open-Circuit Voltage Losses in Perovskite Solar Cells Investigated by Surface Photovoltage Measurement
摘要： Increasing the open circuit voltage (Voc) is one of the key strategies for further improvement of the efficiency of perovskite solar cells. It requires fundamental understanding of the complex optoelectronic processes related to charge carrier generation, transport, extraction and their loss mechanisms inside a device upon illumination. Herein we report the important origin of Voc losses in methylammonium lead iodide perovskite (MAPI) based solar cells, which results from undesirable positive charge (hole) accumulation at the interface between the perovskite photoactive layer and the PEDOT:PSS hole transport layer. We show strong correlation between the thickness-dependent surface photovoltage and device performance, unraveling that the interfacial charge accumulation leads to charge carrier recombination and results in a large decrease in Voc for the PEDOT:PSS/MAPI inverted devices (180 mV reduction in 50-nm-thick device compared to 230-nm-thick one). In contrast, accumulated positive charges at the TiO2/MAPI interface modify interfacial energy band bending, which leads to an increase in Voc for the TiO2/MAPI conventional devices (70 mV increase in 50-nm-thick device compared to 230-nm-thick one). Our results provide an important guideline for better control of interfaces in perovskite solar cells to improve device performance further.
关键词： solar cell,open circuit voltage,perovskite,voltage loss,surface photovoltage
更新于2025-09-16 10:30:52
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Ultrasonically sprayed-on perovskite solar cells-effects of organic cation on defect formation of CH3NH3PbI3 films
摘要： Methylammonium lead iodide (CH3NH3PbI3) based perovskite having low degrees of the disorder is of great interest for optoelectronic and photovoltaic applications. In this work, a layer of CH3NH3PbI3 was successfully prepared using an ultrasonically sprayed-nebulous method. Changes in structural and optical properties alongside with photo-induced charge separation and transportation behavior were systematically studied. The surface photovoltage spectra reveal a significant reduction of the density of deep defect states as the organic content was increased. It was observed that the measured values of Urbach energies decrease from 33.36 to 28.24 meV as the amount of organic content was increased to an optimum value. The best perovskite solar cells obtained using the sprayed-on approach exhibited a Jsc of 16.54 mA/cm2, a Voc of 0.99 V, and a FF of 62.4, resulting in an overall PCE of 10.09%.
关键词： Ultrasonic-sprayed perovskite,Defect states,Surface photovoltage
更新于2025-09-16 10:30:52
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GaAsSbN-based p-i-n heterostructures for solar cell applications grown by liquid-phase epitaxy
摘要： We present an original study on quaternary GaAsSbN layers and multilayer heterostructures grown by low-temperature liquid-phase epitaxy (LPE) on GaAs substrates aiming to explore their potential for photovoltaic applications. We choose Sn and Mg as suitable dopants for practical use. Our experiments on doping reproducibly show the introduction of controlled concentrations of doping impurities in the range applicable to device fabrication. High-quality n-, p- and nearly compensated GaAsSbN layers covering a large range of carrier concentrations from 1015 to 6 × 1018?cm?3 have been grown at temperatures lower than 600?°C. The successful LPE growth of p-i-n GaAs/GaAsSbN/GaAs heterostructures based on closely compensated i-GaAsSbN is demonstrated for the first time. Temperature-dependent photoluminescence and room temperature surface photovoltage contactless characterization techniques have been used for investigation of the grown structures. These measurements have revealed high optical quality with a low concentration of localized states and red photoresponse limit extended down to 1.2?eV.
关键词： doping,GaAsSbN,solar cells,surface photovoltage,photoluminescence,liquid-phase epitaxy
更新于2025-09-12 10:27:22
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Composited micropores constructed by amorphous TiO2 and graphene for degrading volatile organic compounds
摘要： The adsorption ability and photoactivity of photocatalysts directly determine the mineralization efficiency of volatile organic compounds. In this study, a 2D–2D microporous structure of amorphous TiO2 nanoparticles and graphene (GR) was constructed to simultaneously enhance the adsorption ability and charge separation efficiency of catalysts. N2 adsorption–desorption, scanning electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction measurements were conducted to investigate the physical properties of the prepared samples. The atmospheric surface photovoltage (SPV) was utilized to study the separation process of the photogenerated charge carriers. Toluene was chosen as the model agent to estimate the adsorption ability and photoactivity of the samples. Results showed that the amorphous TiO2 nanoparticles homogeneously deposited onto the GR surface and hence formed a 2D–2D microporous structure. Although the surface area of the GR–TiO2 compositions increased by only 4–8% relative to that of microporous TiO2 alone, the amount of adsorbed toluene for the GR–TiO2 compositions was 156–193% times higher than that for the microporous TiO2. The SPV result proved that the GR significantly enhanced the intrinsic separation of the photogenerated charge carriers. The contribution of O2 and the GR to the charge separation was dependent on the weight addition ratio of the GR. The GR dominated the charge separation process as its weight addition ratio ≥5%. Given the advantages in adsorption ability and photoactivity, toluene showed mineralization efficiencies for the composite with 5.0 wt% GR of 1.4 and 2.7 folds those of microporous TiO2 and P25, respectively, after 96 min irradiation.
关键词： Charge carriers,Surface photovoltage,Micropore,Mineralization,Adsorption
更新于2025-09-10 09:29:36
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Improved photoelectric properties of BiOBr nanoplates by co-modifying SnO2 and Ag to promote photoelectrons trapped by adsorbed O2; 通过SnO2和Ag共修饰促进光生电子捕获氧气改善BiOBr纳米盘的光电特性;
摘要： It is highly desired to improve the photoelectric property of nanosized BiOBr by promoting the photogenerated charge transfer and separation. Herein, SnO2 and Ag co-modified BiOBr nanocomposites (Ag-SO-BOB) have been prepared through a simple one-pot hydrothermal method. Surface photovoltage response of BiOBr nanoplates has 4.1-time enhancement after being modified with SnO2 nanoparticles. Transient-state surface photovoltage (TS-SPV) and the atmosphere-controlled steady-state surface photovoltage spectroscopy (AC-SPS) confirmed that this exceptional enhancement of the photovoltage response can be ascribed to the coupled SnO2 acting as platform for accepting the photoelectrons from BiOBr so as to prolong the lifetime and enhance charge separation. Remarkably, the surface photovoltage response can be further enhanced by synchronously introducing Ag nanoparticles, which is up to 15.4-times enhancement compared with bulk BiOBr nanoplates. The enhancement can be attributed to the improved O2 adsorption by introducing Ag to further enhance charge separation. Finally, the synergistic effect of SnO2 and Ag co-modification enhances the surface photovoltage response due to the enhanced charge separation and promoted O2 adsorption, which is also confirmed through photoelectrochemistry and photocatalytic experiment.
关键词： surface photovoltage response,O2 adsorption,charge separation,photoelectron trapping,Ag-SnO2-BiOBr
更新于2025-09-10 09:29:36