Manipulating Crystallization of Organolead Mixed-Halide Thin Films in Antisolvent Baths for Wide-Bandgap Perovskite Solar Cells

Wide..bandgap perovskite solar cells (PSCs) based on organolead (I, Br) mixed halide perovskites (e.g., MAPbI(2)Br and MAPbIBr(2) perovskite with bandgaps of 1.77 and 2.05 eV, respectively) are considered as promising low-cost alternatives for application in tandem or multijunction. photovoltaics (PVs). Here, we demonstrate that manipulating the crystallization behavior of (I, Br)-mixed halide perovskites in antisolvent bath is critical for the formation of smooth, dense thin films of these perovskites. Since the growth of perovskite grains from a precursor solution tends to be more rapid with increasing Br content, further enhancement in the nucleation rate becomes necessary for the effective decoupling of the nucleation and the crystal-growth stages in Br-rich perovskites. This is enabled by introducing simple stirring during antisolvent-bathing, which induces enhanced advection transport of the extracted precursor-solvent into the bath environment. Consequently, wide-bandgap planar PSCs fabricated using these high quality mixed-halide perovskite thin films, Br-rich MAPbIBr(2), in particular, show enhanced PV performance.