Mixed‐Polymer Hole Transport Layers Reinforce Au‐Anode Top Emitting Perovskite Light Emitting Diodes

ABSTRACT As metal halide perovskite light‐emitting diodes (PeLEDs) rapidly improve in performance, identifying and resolving factors that limit operational stability is paramount. Compounds released by the perovskite as byproducts of interfacial electrochemistry can react with and compromise various LED layers and diminish performance, particularly corroding and degrading metal anodes. In this study, we use a mixed‐polymer hole transport layer (a mixture of poly(N,N'‐bis‐4‐butylphenyl‐N,N'‐bisphenyl)benzidine (polyTPD) and poly(9‐vinylcarbazole) (PVK)) to stabilize methylammonium lead iodide‐based PeLEDs with Au metal anodes against increasing leakage current under repeated operation and decreased emission intensity under constant driving. We study this layer using a newly developed Au‐corrosion‐based triiodide detection experiment to determine that our mixed hole transport layer interferes with and inhibits triiodide transport, leading to more stable operation.