Yoonseo Nah1,2,Devan Solanki1,Yitong Dong3,Jason Rohr4,Andre Taylor4,Shu Hu1,Edward Sargent3,Dong Ha Kim2
Yale University1,Ewha Womans University2,University of Toronto3,New York University4
Yoonseo Nah1,2,Devan Solanki1,Yitong Dong3,Jason Rohr4,Andre Taylor4,Shu Hu1,Edward Sargent3,Dong Ha Kim2
Yale University1,Ewha Womans University2,University of Toronto3,New York University4
Quasi-two-dimensional (Quasi-2D) metal halide perovskite consists of inorganic quantum wells sandwiched with organic spacers. It has attracted enormous interests due to its large exciton binding energy, tunable emission wavelength, and solution processability. In general, solution-processed quasi-2D perovskites contain multiple quantum slabs with a broad phase dispersity. Inhomogeneity induces charge funneling into the smallest bandgap components, which poses a challenge in achieving deep-blue electroluminescence. Here, we report a film modulation strategy that significantly narrows the quantum well distribution. We show that the phase dispersity in perovskite film is significantly narrowed with controlled, simultaneous evaporation of solvent and antisolvent. Our quasi-2D perovskite shows stable deep-blue electroluminescence with a peak emission wavelength of 466 nm and a narrow linewidth of 14 nm. Light emitting diodes records a maximum luminance of 280 cd m<sup>-2 </sup>at an external quantum efficiency of 0.1%. This synthetic approach will pave a way to produce new materials that widen the color gamut of next-generation displays.