Research On The Effect Of Zn Doped CH₃NH₃PbI₃ On Photoelectric Properties Of Photovoltaic Cells

There are many problems with the commonly used perovskite photovoltaic material CH₃NH₃PbI₃?MAPbI₃?,such as high toxicity,poor stability and inability to light absorption above 800 nm.To solve these problems,in this paper,a new type of perovskite photovoltaic material MAPb_1-xZn_xI₃ was prepared by using Lewis acid-base theory and one-step spin coating method to replace part of Pb²⁺with low toxicity,small radius and low cost Zn²⁺in transition metal,and the modified material was applied to mesoscopic hole-conductor-free perovskite solar cells based on carbon counter electrodes,the effects of different Zn²⁺doping contents on the photoelectric properties of photovoltaic cells were studied.Then,based on the research on the properties of MAPb_1-xZn_xI₃ photovoltaic cells,some of MA⁺were replaced by Cs⁺to study the effects of Cs⁺doping on the photoelectric properties and hygrothermal stability of photovoltaic cells.The main research work of this paper is as follows:?1?After replacing part of Pb²⁺with 1 mol%of Zn²⁺,the surface morphology and crystallinity of the perovskite films were significantly improved,the grain size,density and coverage were increased,thus reducing the number of grain boundaries and defects in the film and the non-radiative recombination loss was greatly reduced.At the same time,it could reduce the band gap and broaden the absorption spectrum to the near infrared region after replacing part of Pb²⁺with Zn²⁺.?2?After the MAPb_0.99Zn_0.01I₃ was applied to mesoscopic hole-conductor-free perovskite solar cells based on carbon counter electrodes,the overall properties of the photovoltaic cells were largely improved:it not only enhanced and broadened the absorption spectrum of the photovoltaic cells,but also increased the power conversion efficiency from 13.39%to 15.37%,with an increase of 14.8%;moreover,the photoelectric properties of the photovoltaic cells showed excellent reproducibility,and the effect of hysteresis were suppressed.?3?After replacing part of MA⁺with 10 mol%of Cs⁺,the crystallinity and deposition rate of the perovskite films were improved,leading to a decrease in the grain size of the perovskite and an increase in the thickness of the film,and slightly increased the band gap of the material.After multi-doping,the absorption spectra and defect densities of the formed MA_0.9Cs_0.1Pb_0.99Zn_0.01I₃ perovskite films were between MAPbI₃ and MAPb_0.99Zn_0.01I₃ perovskite films,and the hygrothermal stability of the photovoltaic cells was improved,the J_SC,V_OC,FF and PCE were 22.88 mA/cm²,1.04V,63.3%and 15.06%,respectively.In conclusion,the new perovskite materials MAPb_0.99Zn_0.01I₃ and MA_0.9Cs_0.1Pb_0.99Zn_0.01I₃ were prepared by sequentially incorporating Zn²⁺and Cs⁺into MAPbI₃,and then applied to mesoscopic hole-conductor-free perovskite solar cells based on carbon counter electrodes,the photoelectric properties and hygrothermal stability of the photovoltaic cells could be significantly improved,so the problems in MAPbI₃ were solved to some extent.