Study On Preparation Of High Performance Perovskite Solar Cells By Additive Engineering

As global warming,deterioration of the ecological environment and shortage of conventional energy continue to emerge,solar energy is expected to be an important source of energy for the future.With the advantages of simple preparation method,adjustable band gap,high carrier mobility and large absorption coefficient,perovskite solar cells are considered to be a very promising photovoltaic device.Compared with the silicon-based solar cells that now occupy the market,the photoelectric conversion efficiency of PSCs is also similar（the efficiency of single crystal silicon solar cells is about 25%）。The development of PSCs is very rapid,with a record of 24.2% in 2019!Surprisingly,in January 2018,the Swiss EPFL further updated the world efficiency record of perovskite solar cells to 23.3%.In order to promote the further development of PSCs,much more needs to be studied in depth.The quality of the perovskite light absorbing layer is particularly important for the performance of PSCs,not only its morphology,but also its crystallization properties,defect density,and number of grain boundaries.In this paper,the additive engineering method is used to optimize the experimental conditions to prepare high-quality perovskite films,thereby improving the photoelectric conversion efficiency of PSCs.The main research contents and results are as follows:（1）The perovskite light absorbing layer is surface-modified by a solvent treatment method.Nickel phthalocyanine（NiPc）is dissolved as an additive into the anti-solvent chlorobenzene（CB）to form a mixture.Prior to completion of the perovskite crystallization,the mixture is infiltrated into the perovskite surface to improve the interfacial contact of the perovskite with the HTM.This method improves the crystal quality of the perovskite film,the charge transfer efficiency,and effectively suppresses the recombination of carriers.The photoelectric conversion efficiency of the best PSCs was as high as 19.18% and the fill factor（FF） was 74.38%.（2）The non-radiative recombination loss of the interface is one of the main challenges faced by PSCs,which seriously affects the optoelectronic performance,stability and reproducibility of the device.A high quality perovskite film is prepared by incorporating tetrabutylammonium bromide（TBAB）as an additive into the perovskite precursor.Tetrabutylammonium bromide can passivate the surface of the perovskite film,increase the coverage of the perovskite film,reduce the number of pinholes in the film,and reduce the density of the trap state of the film,and the non-radiative recombination of the interface is reduced.The assembled optimal device has a PCE of 20.16% and an open circuit voltage(V_oc) of 1.119V,which is 2.6% higher than the PCE of the original device.（3）An appropriate amount of bis-butylammonium dichromate（TBADC）was added to the hole transport layer precursor（spiro-OMeTAD）to prepare a high-quality pinhole-free hole transport layer.TBADC can oxidize spiro-OMeTAD and improve the quality of HTL film,improve the carrier extraction rate,reduce the non-radiative recombination of HTL/perovskite interface,and improve the photovoltaic performance of PSCs.The assembled PSCs had a photoelectric conversion efficiency of 19.3% and a V_oc of 1.126V.