Research On Electrode/Perovskite Interface Properties And Photodetector Performance

In the last decade,a new hybrid semiconductor optoelectronic material,hybrid organic-inorganic perovskite,has become a"star"material in the field of new energy and optoelectronic information technology due to its excellent properties,which has aroused great interest in the research and industry circles.Numerous research results have shown that the interface between the perovskite and the electrode has a significant impact on the fundamental performance and long-term stability of the device.It is very important to study the interfacial properties of perovskite optoelectronic devices under illumination for understanding the device working mechanism and improving the devices’performance and long-term stability.In this thesis,according to the transfer length method（TLM）,we designed photodetectors with different channel lengths and tested and analyzed the devices’photocurrents,photoresponses,contact resistances,channel resistances and other parameters under different light intensities.Based on the simulation and experiment results,the defects generation mechanism and energy band model were presented,and the changes of carrier transport at the electrode/perovskite interface under different light intensities were investigated.The results show that illumination conditions have a significant effect on the electrode/perovskite interface properties and photodetector performance in the working condition.The specific research works in this thesis are demonstrated below:（1）Combined with the TLM and Silvaco Atlas device simulation,the change of the contact resistance of the interface between the methylamine lead iodide perovskite（MAPb I₃）thin film and the indium tin oxide（ITO）electrode with illumination was studied and analyzed.The results show that the trend of experiment and simulation results is consistent,and the contact resistance of the ITO/MAPb I₃interface decreases with the increase of light intensity.（2）Based on TLM research and analysis,the change of the contact resistance of the interface between the MAPb I₃film and the gold（Au）electrode with illumination was extracted,and the change law of the specific contact resistance of the Au/MAPb I₃interface under illumination was further extracted.Based on the metal-semiconductor contact theory and the semiconductor surface photovoltaic effect,the changing mechanism of interface properties and device performance under illumination was theoretically analyzed.The results show that both the contact resistance and specific contact resistance of the Au/MAPb I₃interface decrease with the increase of the light intensity.Compared with the ITO/MAPb I₃interface,the contact resistance of the Au/MAPb I₃interface has a weaker response to illumination.It is speculated that the formation of the local electric field caused by the enhanced illumination may be the main reason for the decrease of the interface contact resistance.In addition,the interfacial electrochemical reactions and Fermi level pinning will also affect the interfacial properties and device performance.