Research On Structure Regulation And Photoelectric Properties Of Tin-lead Alloy Perovskite

In recent years,organic-inorganic hybrid perovskite solar cells have been developed rapidly,and the power conversion efficiency（PCE）of which surged to25.5%from the original 3.8%during the period of ten years or so,which can rival with the most popular commercialized silicon-based and other thin-film-based solar cells.However,there are still some issues to be resolved to the future large-scale commercialized applications:Problem one,perovskite solar cells are not environmentally friendly,toxic.This is because the highly efficient perovskite solar cells reported so far often contain the toxic element lead;Problem two,instability.The presence of organic ions in organic-inorganic mixed perovskite leads to easy decomposition under hot and humid environmental conditions.Herein,in this work,to attain the high-efficient perovskite solar cells with high stability and low-toxicity,systematic exploration and investigation are performed on the decoration,modification and devices performance of the perovskites.The details as below:1、Inorganic Cs cation and bivalent Sn cation are used to construct a new all-inorganic CsSn_0.3Pb_0.7I₂Br perovskites by replacing or substituting organic cation and Pb cation in the traditional organic-inorganic hybrid perovskites,respectively.To further improve the stability of the perovskites and devices,compositional engineering with organic big molecule-PEABr is conducted in CsSn_0.3Pb_0.7I₂Br perovskites and a high dense and uniform perovskite film with adjustable bandgap is obtained and as a result,the highest PCE of 7.07%of the solar cells with inverse structure based on this film is attained finally.2、The PCE of CsSn_0.3Pb_0.7I₂Br-based perovskite solar cells is far lower than expected in spite of the nice perovskite film with uniform and high dense,in which high bandgap might be the main factor due to the presence of the Br anion.Accordingly,based on CsSn_0.3Pb_0.7I₃perovskites without Br,2D&3D mixed Ruddlesden-popper perovskites is obtained by structural modification with the PEAI additive.The influences of the additive on optical properties,morphologies,structures and chemical compositions are systematically investigated and results show 2D layers in the Ruddlesden-popper perovskites are preferentially grown vertically to the substrates and connected to 3D layers seamlessly,which are prone to improve the capability of the transportation of the photogenerated electrons.PCE over 10%is thus attained in the perovskite solar cells with good stability based on this 2D&3D functional perovskites.These high efficient and stable perovskites with low toxicity are regarded as promising materials to be served as absorption functional layers in the high-efficient perovskite or tandem solar cells.