Interface Passivation And Its Effect On Device Performance In Inverted Wide-Bandgap Perovskite Solar Cells

Perovskite solar cells have become one of the most promising photovoltaic technologies in the field of solar cells because of their high efficiency and low cost.Wide-bandgap perovskite materials with band gap between 1.65 eV and 1.75 eV can be obtained by proportional tune of components for the preparation of perovskite/crystalline silicon solar cells,and the theoretical power conversion efficiency is more than 45%.Due to its low parasitic absorption and matching with heterocrystalline silicon solar cell structure,inverted structured wide-bandgap PSCs have become the first choice to fabricate efficient perovskite/silicon solar cells.Nevertheless,the wide-bandgap perovskite solar cells suffer from insufficient efficiency and stability,which severely limit the performance of tandem devices.The main manifestation of the poor efficiency is the serious non-radiative recombination caused by the interfaces of wide-bandgap perovskite films,resulting in a large loss of open-circuit voltage compared to the theoretical value.The stability problem is mainly due to phase segregation caused by the migration of iodine and bromine ions.Therefore,this work aimed to improve the efficiency and stability of inverted wide-bandgap gap perovskite solar cells by modifying the top and buried interfaces of wide-bandgap perovskite films to reduce non radiative recombination and suppress phase segregation.There are serious problems of photophase segregation in wide-bandgap perovskite.In this paper,three different halide ions,n-butylammonium chlorine(BACI),n-butylammonium bromine(BABr),and n-butylammonium hydroiodide(BAI),were introduced into the perovskite layer interface,and their effects on widebandgap perovskite materials and devices were compared.At the same time,the modification of BACI has been systematically studied,and it is found that The Cl-in BACl could be successfully incorporated into the perovskite lattice to form the triplehalide passivation layer,which possessed higher cohesive energy.As a result,the opencircuit voltage of the p-i-n PSCs with an optical Eg of 1.66 eV is increased from 1.06 V to 1.14 V.resulting in a power conversion efficiency of 18.33%.The device maintained over 80%of its initial efficiency after 440 h of aging under continuous illumination and over 90%of its initial efficiency after 7 h of aging under an 85%relative humidity(RH)ambient condition at room temperature.Secondly,in order to improve the buried interface characteristics of wide-bandgap perovskite layer(hole transport layer/perovskite layer interface),this paper introduced small molecular organic functional material sodium benzenesulfonate(STS)at the PTAA/perovskite interface,which effectively improved the wettability of perovskite precursor solutions on PTAA.The perovskite grains were longitudinally connected and the crystallinity was enhanced,which was conducive to better carrier transport.In addition,it was found that the modification of the buried interface of STS enhances the ability of hole transport,and the sulfonic acid group of STS could effectively passivate the buried interface defects of perovskite layer and inhibit the non-radiative recombination.Finally,the open-circuit voltage and short circuit current of interface modified devices based on STS were significantly improved,and the power conversion efficiency was increased from 16.60%to 18.35%.In general,the two interfacial modification processes of butylamine halide and benzene sulfonate effectively passivated the surface defects of wide-bandgap perovskite and inhibited phase segregation,ultimately achieving the goal of improving the efficiency and stability of inverted wide-bandgap perovskite devices.