Edge stabilization in reduced-dimensional perovskites
Li Na Quan, Dongxin Ma, Yong‐Biao Zhao, Oleksandr Voznyy, Haifeng Yuan, Eva Bladt, Jun Pan, F. Pelayo Garcı́a de Arquer, Randy P. Sabatini, Zachary Piontkowski, Abdul‐Hamid Emwas, Petar Todorović́, Rafael Quintero‐Bermudez, Grant Walters, James Z. Fan, Mengxia Liu, Hairen Tan, Makhsud I. Saidaminov, Liang Gao, Yiying Li, Dalaver H. Anjum, Nini Wei, Jiang Tang, David W. McCamant, Maarten B. J. Roeffaers, Sara Bals, Johan Hofkens, Osman M. Bakr, Zheng‐Hong Lu, Edward H. Sargent
Abstract
Abstract Reduced-dimensional perovskites are attractive light-emitting materials due to their efficient luminescence, color purity, tunable bandgap, and structural diversity. A major limitation in perovskite light-emitting diodes is their limited operational stability. Here we demonstrate that rapid photodegradation arises from edge-initiated photooxidation, wherein oxidative attack is powered by photogenerated and electrically-injected carriers that diffuse to the nanoplatelet edges and produce superoxide. We report an edge-stabilization strategy wherein phosphine oxides passivate unsaturated lead sites during perovskite crystallization. With this approach, we synthesize reduced-dimensional perovskites that exhibit 97 ± 3% photoluminescence quantum yields and stabilities that exceed 300 h upon continuous illumination in an air ambient. We achieve green-emitting devices with a peak external quantum efficiency (EQE) of 14% at 1000 cd m −2 ; their maximum luminance is 4.5 × 10 4 cd m −2 (corresponding to an EQE of 5%); and, at 4000 cd m −2 , they achieve an operational half-lifetime of 3.5 h.