Achieving Well-Oriented FAPbI₃ Perovskite Photovoltaics by Cyclohexane Modification

It is essential and challenging to develop green and cost-effective solar cells to meet the energy demands. Solar cells with a perovskite light-harvesting layer are the most promising technology to propel the world toward next-generation solar energy. Formamidinium lead tri-iodide (FAPbI₃)-based perovskite solar cells (F-PSCs), with their considerable performance, offer cost-effective solar cells. One of the major issues that the PSC community is now experiencing is the stability of α-FAPbI₃ at relatively low temperatures. In this study, we fabricated FAPbI₃-PSCs using cyclohexane (CHX) material via a two-step deposition method. For this purpose, CHX is added to the formamidinium iodide:methylammonium chloride (FAI:MACl) solution as an additive and used to form a better FAPbI₃ layer by controlling the reaction between FAI and lead iodide (PbI₂). The CHX additive induces the reaction of undercoordinated Pb²⁺ with FAI material and produces an α-FAPbI₃ layer with low charge traps and large domains. In addition, the CHX-containing FAPbI₃ layers show higher carrier lifetimes and facilitate carrier transfer in F-PSCs. The CHX-modified F-PSCs yield a high champion efficiency of 22.84% with improved ambient and thermal stability behavior. This breakthrough provides valuable findings regarding the formation of a desirable FAPbI₃ layer for photovoltaic applications and holds promise for the industrialization of F-PSCs.