Quaternary alkylammonium salt incorporated 2D/3D mixed halide perovskite with highly enhanced photoluminescence and arrested iodide/bromide phase segregation

A mixed-halide (I/Br) 2D/3D perovskite is formed by incorporating bromide via quaternary alkylammonium salt and iodide via methylammonium iodide. The X-ray diffraction analysis reveals the 2D/3D mixed constitution, with both components having mixed halide stoichiometry. Importantly, this tetrabutylammonium incorporated material not only exhibits almost two orders of magnitude enhancement of photoluminescence intensity but concurrently a higher photo-stability (at the desirable bandgap of 1.77 eV) than the pure 3D mixed halide case. Moreover, a significant increase (from 8.8 ns to 63 ns) is observed in the lifetime of the photo-generated carriers in the mixed halide 2D/3D material.