Hydrogen-Bond-Mediated Crystallization Kinetics Engineering for Efficient Blue Perovskite Light-Emitting Diodes

Despite significant advancements in green- and red-emitting devices, challenges remain in blue perovskite light-emitting diodes (PeLEDs), particularly in terms of material optimization, doping engineering, and crystallization dynamics. In this work, to address critical inefficiencies and nonradiative recombination losses, we present a simple yet effective approach involving a one-step self-organization process through incorporation of tetraphenylphosphonium chloride (TPPCl). The chlorine atoms in TPPCl, owing to their strong electronegativity, form hydrogen-bonding interactions with the protonated −NH3+ groups in phenethylammonium cations, regulating the crystallization kinetics and thus suppressing the formation of low-dimensional phases. The optimized crystallization process in perovskite thin films facilitates the reduction of trap states and thus exhibits an enhanced exciton binding energy from 53.9 to 58.18 meV. This strategy enables precise control over the reduced-dimensional phases, nonradiative recombination pathways, and spectral stability of the active perovskite layer. The resultant blue PeLEDs achieve a peak external quantum efficiency of 21.2%, representing a 2-fold enhancement compared to control devices (10.3%). Notably, the emission peak of the devices, located at 485 nm, remains stable under varying bias conditions. Our findings highlight that the performance of PeLEDs can be effectively optimized by modulating the perovskite crystallization process and phase distribution, offering a novel strategy for designing multifunctional molecules.