Synthesis Of New Hole Conductors For Enhanced Photovoltaic Performance Of Perovskite Solar Cells

Energy crisis and environmental pollution are two problems of the most serious problems presently faced on 21 century.Therefore,it is really urgent to develop a kind of green renewable energy,which is used as one of the effective strategies to solve above-mentioned issues.In recent years,as the most environmentally-friendly energy,the solar power has attracted extensive attention for its universality and non-toxicity.The solar cells is the most important device to utilize the sunlight.Recently,organic-inorganic hybrid perovskite solar cells have ignited great interest among scientists and technologists due to their simple fabrication procedure and high performance.A typical perovskite solar cell is composed of five parts:compart layer,electron transport layer,perovskite layer,hole transport layer and metallic cathode layer.As an important part of perovskite solar cells,hole transport materials?HTM?can rapidly transfer photogenerated holes,which can greatly improve the photoelectric performance.However,the HTM was mainly limited to organic compounds,such as spiro-MeOTAD.The relatively high cost,complex process of synthetic route may present a potential block for further large-scale application.For this reason,developing alternative hole conductors to substitute spiro-OMeTAD is a promising avenue.In this study,inorganic perovskite KPbI₃ and amorphous TiO₂ as new hole conductor for enhanced the photovoltaic performance of perovskite solar cells.The details are as follows:1)The inorganic perovskite KPbI₃ was synthesized by thermal treatment at 350for 2 h in a stoichiometric mixture of KI and PbI₂ at nitrogen atmosphere.Then different contents of KPbI₃ as HTM were applied in perovskite solar cells.It was found that the efficiency of cells with KPbI₃ as HTMs could be improved compared with the cell without KPbI₃.When the amount of KPbI₃ as hole transport material was controlled to be 3 wt%,the perovskite solar cell displayed the highest activity?4.95%?,which was higher than that of cell without KPbI₃?2.53%?by a factor of 2.If therGOascathodelayerreplacedthePtelectrode,thecell performance further improved to 5.85%.The high conversion efficiency can be attributed to the following reasons:?a?The inorganic perovskite KPbI₃ acts as a hole-capture center to transfer holes efficiently,which can lead to reduction the recombination rate of photogenerated electeon-hole pairs in the perovskite;?b?Interface resistance of perovskite and metal electrode decreased owing to direct contact,which can increase the charge transfer.This work provide a new idea for the design and development of new hole conductors in perovskite solar cell.2)The amorphous TiO₂?a-TiO₂?was prepared by chemical-hydrolyzation reaction using tetra butyl titanate?TBOT?as the precursor.The photoelectric conversion performance of all samples with different concentrations of a-TiO₂ were investigated.The results showed that the cells with a-TiO₂ as HTM displayed the higher conversion efficiency than the cell without a-TiO₂.When the amount of a-TiO₂as hole transport materials was controlled to be 1 wt%,the perovskite solar cell displayed the highest activity?7.71%?,which was higher than that of cell without a-TiO₂?1.70%?by a factor of 4.5.The enhanced conversion efficiency can be attributed to the following reasons:?a?a-TiO₂ as the hole conductor can improve the performance via the rapid capture hole by interfacial oxygen vacancy;?b?the nanoparticles of a-TiO₂ can not only improve the smoothness of film but also reduced the interface resistance.The present amorphous TiO₂ are apparently low-cost,nontoxic,and earth-abundant,which can widely be applied in the design and development of hole transport materials to enchance the photoelectric performance.