Research On The Properties Of Bi-Halide MAPbI_3-xBr_x Perovskites Semitransparent Solar Cells And Copolymers Hole Transporting Materials Based On Thiazolothiazole-Dithienosilole

Organic-inorganic hybrid perovskite solar cell?pero-SC?is considered as the forerunner of the next generation solar cell.As an emerging photovoltaic technology,pero-SC has the advantages of wide material sources,low cost and high power conversion efficiency.The optoelectrical properties of transporting layers and photoactive layer are crucial for the performance of pero-SC.In this thesis,we focus on the tuning of optical and electronic properties depending on the nature of charge transporting materials and perovskite materials via interfacial engineering and composition engineering,specifically as follows:1.At the cathode side of n-i-p type pero-SC,vacuum-evaporated fullerene was employed as interlayer between TiO₂ and perovskite layers.Owing to the high electron affinity of fullerene,the efficiency of electron extraction and transportation was improved as fullerene inserted,the transport resistances were reduced after interfacial modification as well.At the anode side,two novel copolymers,PDTSTTz and PDTSTTz-4 were employed as hole transporting materials.In comparison with pristine Spiro-OMeTAD or P3HT,PDTSTTz and PDTSTTz-4 have advantages of higher hole mobilities due to enhanced backbone planarity and strong?-stacking properties.On the other hand,the broad absorption of copolymers enhances the light harvesting ability of pero-SC,leading to higher photocurrents.Suitable band alignments provided efficient hole transporting and electron blocking.Devices based on novel copolymers shows higher performance than that based on P3HT.2.In composition engineering,Br and I bi-halide MAPb I_3-xBr_x perovskites was synthesized,and applied as photoabsorber to fabricate semitransparent pero-SC.In comparison with MAPbI₃,MAPb I_3-xBr_x showed larger and regular crystallites with improved crystallinity.Upon doping of Br,the bandgap of perovskite became wider,and a lower binding energy was detected by temperature-dependent photoluminescence?T-D PL?.By controlling the ratio of Br and I,the transparency of the perovskite films were greatly improved,and a fairly high photovoltaic performance of pero-SC was obtained.This research demonstrate that bi-halide perovskite MAPb I_3-xBr_x can be a promising candidate for the semitransparent pero-SC.