Thioacetamide-Assisted Crystallization of Lead-Free Perovskite Solar Cells for Improved Efficiency and Stability

Perovskite solar cells (PSCs) have made great strides in recent years, operating inside the theoretical Scholkely-Quisser efficiency limit with a certified power conversion efficiency (PCE) of 26.1%. However, lead toxicity from Pb-based PSCs can harm the environment. As a result, the search for nontoxic and environmentally friendly substances to replace Pb in perovskites is the need of the hour. Tin has emerged as the most viable choice to replace Pb, due to its favorable electronic properties and smaller bandgaps of Sn-based perovskites between 1.1 and 1.4 eV, strong charge carrier mobility, and high theoretical efficiency of 32%. Sn vacancies and point defects, on the other hand, are easily produced in Sn perovskites, leading to nonradiative recombination. Furthermore, interfacial flaws and traps impede further performance improvement. In this research, to produce high-quality Pb-free perovskites for high-performance PSCs, a Lewis-base thioacetamide (TAA) is added to the simple FASnI3 perovskite solution. FASnI(3) and TAA additive-based films effectively control perovskite film crystallinity and grain size via Lewis acid-base reaction. The champion FASnI(3) +TAA-based PSC achieves a maximum PCE of 10.67% while paving a facile way for other compositional perovskite analogues to be integrated into highly efficient and operationally stable PSCs.