Performance Optimization And The Influence Of Interface Charge On Perovskite Solar Cells

Organic-inorganic perovskite solar cells with low cost and high efficiency aroused great concern in these years.Improving the efficiency and stability is always attracting researchers' study,and the photoelectrical conversion efficiency surpassed 22%has been made as so far,however the mechanism of stability isn't clear.In this paper,we work on improving the efficiency and studying the relationship between stability and hysterisis.1.Firstly,we explore the methods of fabricating the organic-inorganic perovskite solar cells.After compare the one-step method and two-step method,we find that the reaction procession,active layer crystallization and the surface morphology has all attribute to influence the performance of solar cells,and confirm an optimal condition to fabricate the perovskite solar cell.Furthermore,the hole and electric transport layer is also important,and NiOx and PCBM are choose as hole transport layer and electron transport layer relatively.The efficiency of device is improved from 3%to 17%by optimizing.2.Secondly,we explore the mechanism of perovskite solar cells.The performance of the device with different morphologies shows different characteristics.The device with rough surface is often accompanied with a larger current-voltage hysteresis,which can be adjusted by PCBM film with different thickness,than the one with smooth surface.It is reported that the generation of hysteresis is due to the accumulation of interfacial charge,which leads to the band bending at the interface and further affects the transport and collection of charge.However,the interface charge density of the device with rough surface is also large.So a model has been proposed to explain this phenomenon:the accumulation of interfacial charge is closely relevant with the capacitance of the interface,the larger the capacitance is,the more the charge is accumulated.The rough surface leads to a larger capacitance relative area,and the thin PCBM film will lead to a short distance of the two plate.They are the reasons for the large capacitance of the interface and coincident with our experimental data.So a smooth surface and a suitable thickness of the PCBM layer can reduce the capacitance of the interface and the accumulation of the interfacial charge.