Preparation and optoelectronic properties of multi-color high-efficiency CH₃NH₃Pb(Br_xI_1-x)₃ perovskite light-emitting diodes

Abstract Multi-color light-emitting materials are essential lighting and displays. In this study, mixed halide system was applied to precisely tune the bandgap of CH₃NH₃Pb(Br _x I_1-x )₃, thus regulating the emission wavelength. PEABr was employed to change the phase structure and morphology of CH₃NH₃Pb(Br _x I_1-x )₃ perovskite thin films and improve the performance of multi-color perovskite light-emitting diodes (PeLEDs). Theoretical simulations through first-principles calculations and experiments demonstrate that multi-color PeLEDs can be achieved by adjusting the ratio of bromine (Br) and iodine (I) atoms in the CH₃NH₃Pb(Br _x I_1-x )₃ perovskite. The maximum luminance of PEABr-modified green PeLEDs reached 7108 cd m⁻², with a maximum current efficiency of 8.25 cd A⁻¹ and a maximum external quantum efficiency (EQE) of 1.62%, which were greatly improved compared to the reference device without PEABr. In addition, the luminance of orange-yellow and red mixed-halide PeLEDs both exceed 100 cd m⁻². The results demonstrate that the use of PEABr additive can effectively control the morphology of CH₃NH₃Pb(Br _x I_1-x )₃ crystals, and high-performance multi-color light-emitting devices can be achieved by combining with mixed halide system. The electroluminescence spectra showed that the emission range of the devices covered the wavelength region of 520–720 nm, demonstrating their good application prospects in the field of multi-color displays.