Roles of Sn content in physical features and charge transportation mechanism of Pb-Sn binary perovskite solar cells. (October 2020) - Badrooj, Mohammad
Graphical abstract: Highlights: Crystalline properties of samples were analyzed by the modified Scherer method. At x = 0.25, the morphology of CH3 NH3 Snx Pb1-x I3 changes to cauliflower-like islands. The conductivity of CH3 NH3 Snx Pb1-x I3 converts from p- to n-type at x = 0.25. Increasing Sn, the depletion zone width between the absorber and ETL layer reduces. Abstract: Tin (Sn)-based perovskites are a low-toxic and eco-friendly alternative because of their faster tendency to form inert oxides which have much lower bio-availability than lead-based perovskites. Therefore, at present paper, different properties of Pb-Sn binary perovskite solar cells (CH3 NH3 Snx Pb1 – x I3 [0 ≤ x ≤ 1]) were investigated under ambient conditions without the use of encapsulation techniques. For the first time, cauliflower-like morphologies of Sn/Pb mixed perovskites were synthesized and their structural quantitatively analyzed using modified (Monshi) Scherrer (M-Sch) and Williamson-Hall (W-H) methods. The electrical characterization of the cells revealed that incorporating Sn ions into the Pb-based perovskite not only dramatically reduces the carrier density but also from the molar ratio of x = 0.25 to higher values, it converts the electrical conduction behavior from p- to n-type . This effect could be considered as one of the effective factors in reducing the efficiency (η) of solar cells from 16.83% for CH3 NH3 PbI3 to 0.86% for CH3 NH3 SnI3 . Therefore, choosing an appropriate strategy against this electrical conductivity behavior could help us to achieve a new approach to reducing the toxicity of perovskite solar cells with the least reduction in their efficiency.