Dual‐Defect Manipulation Enables Efficient and Spectrally Stable Blue Perovskite Light‐Emitting Diodes

Abstract

Abstract Performance of blue solution‐processed perovskite light‐emitting diodes (LEDs) is limited by availability of blue perovskite materials. Herein, 4‐(trifluoromethyl)benzoyl ammonium bromide (4‐TMBABr) is used with abundant NH and CO groups to passivate the defects and produce highly stable PEA x PA 2‐x (CsPbBr 3 ) n‐1 PbBr 4 perovskites for blue LED applications. The NH group in the 4‐TMBABr suppresses the Br‐ion mismatch through hydrogen bonds (N‐H···Br) and CO group coordinates the unsaturated lead dangling bonds (CO:Pb). The effective defect passivation by 4‐TMBABr reduces the nonradiative recombination in the perovskite films, hence enhancing its optical performance. In the LED structure, the sodium bis(trifluoromethanesulfonyl)imide (SBTI) modified NiO x films are used to improve the hole transport and to inhibit the fluorescence quenching of the perovskite layer. The dual‐defect manipulation strategy is advantageous for producing efficient and spectrally stable blue perovskite LEDs, and the authors demonstrate an LED with maximum luminance of 1094 cd m −2 and external quantum efficiency of 10.3%. This work can inform and underpin future development of blue perovskite LEDs with highly efficient and stabile performance.