High-Performance Green Light-Emitting Diodes Based on MAPbBr-Polymer Composite Films Prepared by Gas-Assisted Crystallization.

The morphology of perovskite films has a significant impact on luminous characteristics of perovskite light-emitting diodes (PeLEDs). To obtain a highly uniform methylammonium lead tribromide (MAPbBr) film, a gas-assisted crystallization method is introduced with a mixed solution of MAPbBr precursor and polymer matrix. The ultrafast evaporation of the solvent causes a high degree of supersaturation which expedites the generation of a large number of nuclei to form a MAPbBr-polymer composite film with full surface coverage and nano-sized grains. The addition of the polymer matrix significantly affects the optical properties and morphology of MAPbBr films. The PeLED made of the MAPbBr-polymer composite film exhibits an outstanding device performance of a maximum luminance of 6800 cd·m and a maximum current efficiency of 1.12 cd·A. Furthermore, 1 cm area pixel of PeLED displays full coverage of a strong green electroluminescence, implying that the high-quality perovskite film can be useful for large-area applications in perovskite-based optoelectronic devices.