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Interfacing green synthesized flake like-ZnO onto TiO <sub/>2</sub> as a bilayer electron extraction for efficient perovskite solar cells
摘要： To improve the performance of the PSCs, it is essential to prevent the carrier recombination losses at the interfaces of the transparent metal oxide electrode/electron transport layer (ETL) / active absorber perovskite layer. This present work reports about the green synthesis approach used for the preparation of flake like-ZnO nanostructure (GF-ZnO NSs), naturally extracted from the leaf of Albizia Amara - as a reducing cum capping agent. Herein, we have introduced the above prepared an n-type GF-ZnO NSs material as efficient electron transport interfacial layer (bi-ETL) at the ETL/perovskite junction in the fabricated perovskite solar cells (PSCs). The structure of the fabricated PSC device as follow: Glass/ITO/bi-ETL (c-TiO2/GF-ZnO NSs)/CH3NH3PbI3-xClx/Spiro-MeOTAD/Au. A comparative study has also been made by deploying electron transport materials such as c-TiO2 and GF-ZnO NSs separately. From this, it has been found that the bi-ETL perovskite solar cell devices achieved a maximum power conversion efficiency (PCE) of 7.83% with open-circuit voltage (VOC) of 0.728 V, short circuit current density (JSC) of 20.46 mA/cm2 and a fill factor (FF) of 52.61% compared to that of the chemically reduced ZnO based devices. Whereas, the c-TiO2, GF-ZnO NSs and the chemically reduced CR-ZnO based ETL based devices achieved a PCE of 4.84%, 5.82% and 6.81% respectively. The obtained better performance of the bi-ETL based devices is ascribed to the enhanced carrier extraction and the reduced recombination losses at the interface between the ETL and the active perovskite layer.
关键词： bilayer electron extraction,green synthesis,Perovskite solar cells,Interfacial layer,ZnO nanostructure,Albizia Amara leaf extract
更新于2025-09-23 15:19:57
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Construction of Cr2O3:ZnO Nanostructured Thin Film Prepared by Pulsed Laser Deposition Technique for NO2 Gas Sensor
摘要： Rhombohedral structure of chromium oxide (Cr2O3) thin-film doped hexagonal zinc oxide (ZnO) nanoparticles have been prepared using pulsed laser deposition technique at a different weight percent of ZnO from 0 to 9 wt%. The results of X-ray diffraction analysis shown that the doped films are polycrystalline, and the average crystallite size of the synthesized thin films is found to be dependent on the ZnO concentration. The surface morphology of the prepared thin films was characterized by atomic force microscopy. The optical properties are investigated using ultraviolet–visible light (UV–Vis) absorption spectroscopy. The optical bandgap ranged from 2.45 to 2.68 eV, showing the shift towards longer-wavelength compared to bulk Cr2O3 (~ 3 eV). The sensitivity, response, and recovery times of the sensor towards nitrogen dioxide (NO2) gas were studied and discussed. The sensitivity increase with increasing the doping concentration, and started to decrease when ZnO concentrations reach 7 wt%. The optimal ZnO concentrations for NO2 gas sensitivity is 5 wt%, which attain maximum sensitivity of 87.5% at temperature of 523 K.
关键词： Cr2O3:ZnO nanostructure,Structural properties,Optical properties,Gas sensitivity,PLD technique
更新于2025-09-23 15:19:57
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Enhancement of power conversion efficiency of Al/ZnO/p-Si/Al heterojunction solar cell by modifying morphology of ZnO nanostructure
摘要： This paper proposes a cost-effective sol–gel method for synthesis of ZnO nanostructure to make Al/ZnO/p-Si/Al heterojunction solar cell. Here, crystalline ZnO nanostructure was grown on p-silicon and annealed at 300 °C, 400 °C and 500 °C for application in heterojunction solar cell. The optimum temperature for obtaining uniform crystalline nanostructure was 500 °C, as confirmed from XRD and SEM imaging. As investigated by UV–Vis spectroscopy, the ZnO nanostructure layer exhibited high transmittance in the visible spectrum and has a direct band gap of 3.26–3.28 eV. The power conversion efficiency of Al/ZnO/p-Si/Al solar cell is enhanced from 1.06 to 2.22% due to increase in surface area of ZnO by formation of crystalline nanostructure due to increase of annealing temperature. The optimum value of short-circuit current (Isc) and open-circuit voltage (Voc) was measured using current–voltage (I–V) under AM 1.5 illuminations and found to be 9.97 mA and 460 mV, respectively.
关键词： Power conversion efficiency,Sol–gel method,Annealing temperature,Heterojunction solar cell,ZnO nanostructure
更新于2025-09-23 15:19:57
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Resistive Switching in Sub-micrometric ZnO polycristalline Films
摘要： Resistive switching devices are considered as the most promising alternative to conventional random access memories. They interestingly offer effective properties in terms of device scalability, low power-consumption, high read/write operation time, endurance and state retention. Moreover, neuromorphic circuits and synapse-like devices are envisaged with resistive switching modeled as memristors, opening the route toward beyond-Von Neumann computing architectures and intelligent systems. This work investigates how the resistive switching properties of zinc oxide thin films are related to both sputtering deposition process and device configuration, i.e. valence change memory (VCM) and electrochemical metallization memory (ECM). Different devices, with an oxide thickness ranging from 50 to 250 nm, are fabricated and deeply characterized. The electrical characterization evidences that, differently from typical nanoscale amorphous oxides employed for resistive RAMs (HfOx, WOx, etc..), sub-micrometric thicknesses of polycristalline ZnO layers with ECM configuration are needed to achieve the most reliable devices. The obtained results are deeply discussed, correlating the resistive switching mechanism to material nanostructure.
关键词： resistive switching,ZnO,nanostructure,memristors
更新于2025-09-10 09:29:36