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Vapor-deposited all inorganic CsPbBr3 thin films and interface modification with C8-BTBT for high performance photodetector
摘要： All inorganic perovskites like CsPbBr3 have attracted rising attention and are considered as promising candidates for optoelectronic devices. Here we fabricated CsPbBr3 films by co-evaporation. The as-deposited and low temperature (below 300 °C) annealed films are in a mixture phase of CsPbBr3 and CsPb2Br5. After 400 °C annealing in ambient air, the CsPbBr3 phase becomes dominant with a good crystal structure and less defects. Then, 2,7-diocty[1]benzothieno-[3,2-b]benzothiophen (C8-BTBT) was deposited on the CsPbBr3 film layer-by-layer to investigate the interface electronic structure with X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). As C8-BTBT was deposited, p-doping effect was observed at the surface of CsPbBr3 by the interface energy level alignment. At the same time, we also observed a chemical reaction at the interface and a small amount of lead sulfite might be formed. CsPbBr3 based photodetectors with or without C8-BTBT modified layer were also fabricated and studied. It was found that the photocurrent of the detectors with an additional C8-BTBT layer was about two orders of magnitude higher than that without C8-BTBT layer. The responsivities and response time are also improved with C8-BTBT. We attribute the improvement of photoelectronic properties to the interface energy level adjustment by the C8-BTBT. These results highlight the potential of C8-BTBT as a modified layer for inorganic perovskite optoelectronic devices.
关键词： CsPbBr3 films,C8-BTBT,Interfacial electronic structures,Vacuum evaporation,Photoelectronic properties
更新于2025-09-23 15:21:01
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Growth of BaSi <sub/>2</sub> film on Ge(100) by vacuum evaporation and its photoresponse properties
摘要： We have successfully grown a polycrystalline orthorhombic BaSi2 film on a Ge(100) substrate by an evaporation method. Deposition of an amorphous Si (a-Si) film on the Ge substrate prior to BaSi2 evaporation plays a critical role in obtaining a high-quality BaSi2 film. By controlling substrate temperature and the thickness of the a-Si film, a crack-free and single-phase polycrystalline orthorhombic BaSi2 film with a long carrier lifetime of 1.5 μs was obtained on Ge substrates. The photoresponse property of the ITO/BaSi2/Ge/Al structure was clearly observed, and photoresponsivity was found to increase with increasing substrate temperature during deposition of a-Si. Furthermore, the BaSi2 film grown on Ge showed a higher photoresponsivity than that grown on Si, indicating the potential application of evaporated BaSi2 on Ge to thin-film solar cells.
关键词： photoresponse properties,Ge substrate,thin-film solar cells,BaSi2,vacuum evaporation
更新于2025-09-23 15:19:57
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Cold substrate method to prepare plasmonic Ag nanoparticle: deposition, characterization, application in solar cell
摘要： In this study, the surface plasmon effects of the Ag nanoparticle were investigated depending on the substrate temperature and coating time. Deposition procedure for the Ag coating was the vacuum deposition at low substrate temperature (< 300 K) instead of the commonly used the vacuum deposition at high substrate temperatures. The Ag thin films were deposited on n-type Si, glass and solar cell with safety glass substrates. The structural and optical characteristics of the Ag thin films prepared on Si and glass substrates were investigated. The Ag thin films had a polycrystalline structure with cubic phase. The (111) preferred orientation for 300 K substrate temperature was changed to (200) after 200 K substrate temperature. Homogeneous nano-sized Ag particles on Si were obtained at the 150–200 K temperature range. Optical measurements were performed for the Ag thin films prepared on glass substrates. According to reflectance measurements, plasmon resonance effect of the Ag nanoparticles was observed around 435–540 nm. The Ag nanoparticles prepared on solar cell at low substrate temperature increased the solar cell efficiency for all coating time because the nanoparticle size and shape were not changed significantly with the coating time. However, the Ag thin films prepared at high substrate temperature decreased device efficiency with the increasing coating time.
关键词： Surface plasmon resonance,Ag nanoparticle,Vacuum evaporation,Solar cell,Cold substrate
更新于2025-09-19 17:13:59
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Formation of CH <sub/>3</sub> NH <sub/>2</sub> -incorporated intermediate state in CH <sub/>3</sub> NH <sub/>3</sub> PbI <sub/>3</sub> hybrid perovskite thin film formed by sequential vacuum evaporation
摘要： CH3NH3PbI3 thin films were formed with various deposition rates of PbI2 first layer using a sequential vacuum evaporation method (SVE) to understand the formation behavior. Under low PbI2 deposition rates with 1 and 3 ? s?1, the thin films did not form the hybrid perovskite structure. Over the 6 ? s?1 deposition rate, the perovskite structure is observed with the remaining PbI2 and an intermediate phase together. In the 10 ? s?1, the intermediate phase is increased, and the CH3NH2 molecular defect is observed. The hybrid perovskite thin film formed by SVE is confirmed with tiny grains and CH3NH2-incorporated intermediate state.
关键词： CH3NH3PbI3,intermediate phase,CH3NH2 molecular defect,sequential vacuum evaporation,hybrid perovskite
更新于2025-09-10 09:29:36
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Substrate temperature dependent variation in the properties of cadmium telluride thin films deposited on glass
摘要： The present study relates to the variation in properties of cadmium telluride (CdTe) thin films deposited via electron beam and thermal vacuum evaporation methods at two different substrate temperatures. The influence of substrate temperature on structural, morphological, optical and electrical properties of CdTe thin films is investigated. For structural characterization, grazing incidence X-ray diffraction technique is used which revealed that thin films deposited at 200 °C temperature are more crystalline in nature as compare to the room temperature. The parameters such as average crystallite size (D), lattice strain (ε), number of crystallites per unit area (N) and texture coefficient TC (hkl) were calculated for both types of synthesized CdTe thin films. Surface morphology of thin films was recorded using scanning electron microscopy and found to be homogeneous in nature. The optical studies carried out using UV–Visible Spectrophotometer and Photoluminescence shown a decrease in band gap values for both electron beam and thermally deposited thin films samples at 200 °C substrate temperature. Electrical measurements recorded using two probes method showed the maximum value of current for CdTe thin films deposited by electron beam evaporation method at 200 °C substrate temperature.
关键词： Thermal vacuum evaporation,Optical properties,Thin films,Electron beam evaporation,Electrical properties,Structural properties,Substrate temperature,Cadmium telluride
更新于2025-09-09 09:28:46