Knitting Interconnected Perovskite Grains with A Π-Conjugated Passivator for Blue Light-Emitting Diodes

Metal halide perovskite light-emitting diode (PeLED) is the most promising candidate for next-generation display technology. However, the development of the blue PeLEDs is far behind the expectations. Mixed-halide perovskites demonstrate to be the most facile method to realize blue emission, which confronts serious spectra stability problem arising from the halide segregation. Here, a polymerizable passivator is introduced into the Cl/Br-mixed perovskites, which can simultaneously cross-link perovskite grains by interconnecting halides through hydrogen bonding, and transport the carriers through its π-conjugated backbone. Consequently, this cross-linked blue perovskite film demonstrates a significantly improved spectra stability under various external stimuli of high humidity, UV radiation, and electrical field, and the corresponding PeLED yields a decent external quantum efficiency of 12.0% at high brightness of 3390 cd m −2 with the emission at 478 nm. Notably, this work provides a unique cross-link agent with in situ polymerizability to address the ion migration and phase segregation issues without sacrificing the conducting capacity in mixed-halide perovskites.