Effect Of CH₃NH₃PbI₃/PCBM Interfacial Passivation Layer On Performance Of Pervskite Solar Cells

In recent years,with the growth of population and the rapid development of economy,the global demand for energy is expanding,energy depletion and environmental pollution has become an urgent problem to be solved,so it is imperative to find renewable clean energy and realize the effective use Perovskite solar cell(PSC)is a pOpular new type of cell in recent years,is considered to be the most promising alternative energy.It not only owns good photoelectric performance,has a relatively high power conversion efficiency(PCE),and the material cost is lower,but also can be prepared by solution lethod.so as to achieve large-scale commercial production with the echnology of roll to roll.The materials of PSCs have flourished in recent years and have made great achievements with PCE rising from 3.8%(2009)to over 23%.It is an accomplishment that other types of solar cells must take decades to achieve.High efficiency,low cost,low temperature treatment,simple preparation process and other characteristics make perovskite materials and PSCs have great commercial prospect:The PSCs with high PCE and long-term stability mainly depend on high crystal quality of perovskite film,matching level and good interface contact between each layer,so the interface modification work is of great significance to improve the photoelectric performance of PSCs.In this paper,two different materials N2200 and 1,4-Dibromotetrafluorobenzene(14-DBrTFB)were used as the interface modification layer of perovskite/PCBM,which effectively passivate the perovskite layer,thus preparing the high quality CH3NH3PbI3 PSCs.These materials improved the short-circuit current density(Jsc)and PCE of cells,and provides a new scheme for the preparation of low cost and high performance PSCs.The content of this paper is divided into the following two parts(1)The non-fullerene material N2200 containing C=O was used as the interface modification layer between perovskite/PCBM and prepared the PSCs with double electron transport layers(ETLs).Then the morphology of MAPbI3 film was characterized by SEM,XRD and AFM,and a series of measurements were carried out on the photoelectric performance of the complete devices(the device structure is ITO/PEDOT:PSS/CH3NH3PbI31N2200/PC61BM/Bphen/Ag)Compared with the traditional PSCs,N2200/PCBM double ETLs increase the built-in potential of PSCs and reduce the interface barrier of the perovskite/ETL and then result in higher Vo,.Moreover,N2200 can efficiently inhibit the aggregation of PCBM,promote perovskite surface grain growth and passivate perovskite interface defects.All these are beneficial for electron transfer and extraction,and thereby increase the Jsc and the Fill Factor(FF)of N2200 PSCs In addition,N2200 obviously improve the air-and illumination-stability of PSCs.These results could stem from the interaction between PbI2 as Lewis acid and N2200 as Lewis base.The average PCE for N2200 devices is about 15.5%,significantly exceeding the average PCE(about 14.18%)for the devices with only PCBM as ETL.In a word,N2200/PC61BM as double ETLs is an effective strategy to obtain high photovoltaic performance PSCs(2)The cheap organic small molecule 14-DBrTFB was employed as the interface modification layer of perovskite/PCBM to prepare high-quality perovskite film.The morphology of perovskite film was characterized by a variety of means,and the optoelectronic properties of 14-DBrTFB devices(the device structure was ITO/PEDOT:PSS/CH3NH3PbI3/14-DBrTFB/PC61BM/Bphen/Ag)were measured.The effects of 14-DBrTFB on perovskite film and interfaces were systematically studied,and the work mechanism between 14-DBrTFB and perovskite materials was revealed.14-DBrTFB reduced the defects of perovskite film,improved the crystal quality and device performance Furthermore,the inverted 14-DBrTFB solar cell with the maximum PCE of 16.35%was obtained in the experiment.In addition,the material 14-DBrTFB contains a hydrophobic F atom,which can effectively block the erosion of water and oxygen in the surrounding environment,thus improving the stability of perovskite devices.This work provides a simple and low cost effective scheme for preparing the PSCs with high efficiency and stability.