Preparation And Perfomance Of Perovskite Solar Cells

Accompanied by the energy crisis and environmental pollution,more and more people pay their attention to the field of solar energy exploitation and utilization,which can be fabricated with low-cost and large-scale production.Recently,perovskite materials have attracted considerable attention because of its suitable band gap and great charge carrier diffusion length.And the efficiency of perovskite photovoltaic device has made a great progress in a few years.It has recently realized large conversion efficiency over 22%.Besides the high PCE,perovskite does not contain noble elements and can be fabricated by solution process or physical vapor deposition at a low temperature which significantly reduces production costs.Therefore,perovskite solar cells(PSCs)have rapidly triggered research booms and are considered as the new hope of photo voltaic area.PSCs mainly consist of five parts:FTO,electron transport layer,perovskite light absorption layer,hole transport layer and the counter electrode.Among them,the electron transport layer,perovskite light absorption layer and hole transport layer,as important parts of the device structure,are the key factors determining photoelectric conversion efficiency of the solar cells.By developing variety of preparation,doping and modification technologies,thus further improving the effective utilization of solar energy and efficient carrier transport process.It is definitely that the research on solar cells has theoretical significance and application value.In this paper,we have made systematic studies on the preparation and properties of organic-inorganic hybrid PSCs and all-inorganic PSCs.The main contents are summarized as following:(1)In the organic-inorganic hybrid PSCs,we synthesized the MAPbBr3-xIx colloidal quantum dots(QDs)by a simple method at room temperature.And we regulated the size and energy level structure of the MAPbBr3-xIx colloidal quantum dots through composition adjustment.By various of photoelectric performance test methods including UPS,PCE,IPCE and EIS,we selected the most conducive interface layer-MAPbBr3QDs layer,to optimize the device structure of the bromide-based PSCs.We further explored the mechanism of solving the surface defects of electron transport materials and improving the device performance and stability while the interface modification layer was inserted.The results showed that,MAPbBr3 QDs layer,as an interface modification layer used in mesoporous MAPbBr3 PSCs,could reduce the density of surface electron defects in TiO2/MAPbBr3 heterojunction and promote the electrical transrmission from perovskite to electron transport layer.Device photoelectric conversion efficiency was obviously improved(from 5.64%to 8.29%).IPCE and device stability were also significantly enhanced.(2)In all-inorganic PSCs,we inproved the photovoltaic properties of the solar cells through optimizing both the charge transport layer and perovskite light absorption layer.F irst of all,we synthesized the CuGaO2 nanosheet,with high optical transparency and high hole mobility,by the hydrothermal method-It was used as the inorganic hole-transporting material of n-i-p type PSCs.Next,we choosed cesium lead halide perovskite(CsPbI2Br)with high thermal stability as the light absorption layer,then we partly replaced cesium cations with potassium cations and studied Cs1-xKxPbI2Br film by changing the stoichiometry of potassium.By various of structrue and photoelectric performance test methods,we investigated the photovoltaic properties and device stability of all-inorganic Cs1-xKxPbI2Br PSCs based on CuGaO2 hole transport layer(HTL)after incorporating potassium cations.And the results showed that when the K+ ratio satisfied x = 0.075,not only the formation and transport of photocarriers were effectively promoted,but also the crystallinity and surface morphology of the perovskite films were significantly improved.Cesium lead halide PSCs with enhanced performance(from 8.1%to 9.8%)and stability were also demonstrated.In addition,the use of the inorganic HTL-CuGaO2 also significantly enhanced the air stability of device and it provided more possibilities for further research on the all-inorganic PSCs.