Dual-functional additives for stable perovskite thin films

Organic–inorganic lead halide perovskites have emerged as frontrunners in next-generation optoelectronic technologies due to their exceptional optoelectronic properties. Despite remarkable advancements, their commercialization is hindered by their poor intrinsic stability and suboptimal charge-carrier dynamics. In this work, we introduced thionate-based additives, 1-butyl-3-methylimidazolium thiocyanate (BMIM-SCN) and 1-butyl-3-methylimidazolium lead thiocyanate (BMIM-Pb(SCN)₃), as effective chemical modulators to simultaneously enhance the crystallinity, surface quality, and environmental resilience of hybrid perovskite films. The incorporation of these additives facilitates the formation of dense, uniform crystal grains with improved surface coverage and significantly reduced surficial and interfacial trap states. The modified films exhibit superior charge transport behavior and demonstrate remarkable resilience under humid, thermal, and light stress, outperforming their pristine counterparts. Specifically, BMIM-Pb(SCN)₃ is proven to be particularly effective, synergistically enhancing both the charge-carrier mobility and long-term film stability. This dual-functional additive strategy not only passivates defects but also regulates the structural evolution of the perovskite layer, leading to an improved optoelectronic performance. These findings present a viable route for stabilizing hybrid perovskites and advancing their practical deployment in photovoltaic and optoelectronic applications.