Improving the Stability and Performance of Perovskite Light-Emitting Diodes by Thermal Annealing Treatment

The effect of thermal annealing on the morphology and crystallinity of MAPbBr₃ films as well as the performance and long-term stability of PeLEDs were investigated. A continuous perovskite film with high crystallinity was fabricated using a thermal annealing treatment. To obtain uniform and dense MAPbBr₃ films, the MAPbBr₃ layer used as the emissive layer was deposited onto a PEDOT:PSS-coated ITO/glass substrate by spin-casting a 1:1 molar ratio solution of PbBr₂ and MABr in a DMF/HBr cosolvent. The PeLED with a MAPbBr₃ film fabricated under optimized thermal annealing conditions exhibited improved device performance and full coverage of the green electroluminescence (EL) at the turn-on voltage because of the high quality of the continuous perovskite layer, as confirmed by scanning electron microscopy (SEM) and inverted optical microscopy. Moreover, the encapsulated PeLED with the MAPbBr₃ film prepared under the optimized thermal annealing conditions exhibited excellent long-term stability under ambient conditions.