Study On The Performance Optimization Of The Light Absorbing Layer And Electron Transport Layer Of Perovskite Solar Cells With Organic Additives

Organic-inorganic hybrid perovskite has many excellent properties,such as long carrier diffusion length,large light absorption coefficient,and adjustable band gap.Therefore,perovskite materials have huge optoelectronic applications.Perovskite solar cells（PSCs）are thin-film cells with perovskite materials as the light-absorbing layer.The photoelectric conversion efficiency（PCE）has rapidly grown from the initial 3.8%to 25.5%.At present,the application of perovskite solar cells mainly faces two problems,one is the improvement of photoelectric conversion efficiency,and the other is the stability of cell operation.The key to further improving the performance of perovskite solar cells is to improve the quality of the perovskite film,the carrier mobility of the transport layer,and the interface contact between the perovskite and the transport layer.In this paper,based on the ITO/SnO₂/MAPbI₃/Spiro-OMe TAD/Ag forward planar cell structure,the quality of the perovskite film and the electron transport layer is optimized by introducing different organic additives into the perovskite precursor solution and SnO₂ solution,respectively and interface contact.Thereby improving the performance of perovskite solar cells.The main findings of this paper are as follows:（1）The MAPbI₃ perovskite film was prepared by a one-step anti-solvent method,and 3,4,5-trihydroxybenzoic acid（GA）was added to the perovskite precursor solution to control and improve the crystallization of the perovskite.Studies have found that when perovskite films are prepared by anti-solvent spin coating,the carboxyl groups in GA form hydrogen bonds with MA⁺,which can delay the crystallization of perovskite films,increase grain size,reduce defect state density,and improve perovskite solar cells.The photoelectric conversion efficiency and stability.When the amount of GA added is 1%（molar ratio to Pb I₂）,the photoelectric conversion performance of the perovskite solar cell is the best,and the short-circuit current of the device is increased from 21.91 m A·cm^-2 to 22.48 m A·cm^-2,The open circuit voltage was increased from 1.052 V to 1.097 V,and finally a photoelectric conversion efficiency of 16.84%was obtained.（2）The oxygen vacancies in the SnO₂ electron transport layer are the non-radiative recombination centers of carriers,which hinder the transport of carriers.In this paper,thiosemicarbazide（CH₅N₃S,TSC）is added to the SnO₂ precursor solution.The S atoms in TSC form S-Sn bonds with Sn,which reduces the oxygen vacancy defects on the SnO₂ nanocrystals,thereby suppressing carriers.The non-radiative recombination of SnO₂ significantly improves the electron mobility and conductivity of the SnO₂ film.At the same time,a Sn-S-Pb bond is formed at the interface of the SnO₂ electron transport layer and the perovskite layer,which makes the perovskite light absorption layer and the electron transport layer more tightly combined,which is beneficial to the transport of carriers.Under the modification of15 mg TSC,the short-circuit current density of the perovskite solar cell increased from 21.61 m A·cm^-2 to 23.24 m A·cm^-2,and the photoelectric conversion efficiency increased from 15.74%to 18.17%.