Morphology Engineering for High‐Performance and Multicolored Perovskite Light‐Emitting Diodes with Simple Device Structures

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Abstract
The film morphology is extremely significant for solution processed perovskite devices. Through fine morphology engineering without using any additives or further posttreatments, a full-coverage and high quantum yield perovskite film has been achieved based on one-step spin-coating method. The morphologies and film characteristics of MAPbBr3 with different MABr:PbBr2 starting material ratios are in-depth investigated by scanning electron microscopy, atomic force microscopy, X-ray diffraction, photoluminescence, and time resolved photoluminescence. High performance organometal halide perovskite light-emitting didoes (PeLEDs) based on simple device structure of indium tin oxide/poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS)/perovskite/TPBi/Ca/Al are demonstrated. The green PeLED based on MAPbBr3 shows a maximum luminance of 8794 cd m−2 (at 7.3 V) and maximum current efficiency of 5.1 cd A−1 (at 5.1 V). Furthermore, a class of hybrid PeLEDs by adjusting the halide ratios of methylammonium lead halide (MAPbX3, where X is Cl, Br, or I) are also demonstrated at room temperature. These mix-halogenated PeLEDs show bright luminance (above 100 cd m−2) with narrow and clean emission bands over the wide color gamut.