Multifunctional Molecule-Assisted Crystallization Control for Efficient Perovskite Light-Emitting Diodes

Three-dimensional (3D) perovskite with good charge transport and structural stability, showing application potential in light-emitting diodes (LED). However, the grain size of 3D perovskite in the liquid-solid process is relatively large and large amounts of defects on the grain surface and grain boundaries were produced, leading to a reduced efficiency of LED devices. Herein, we report a dual rivet strategy to regulate perovskite growth kinetics in liquid-solid processes by introducing 3-(Hydroxy(phenyl) phosphoryl)propanoic acid (CEPPA) into the perovskite precursor. CEPPA has a dual coordination functional group, which can simultaneously form covalent bonds with two uncoordinated lead atoms on the surface of perovskite, effectively controlling the crystals during the liquid-solid process and obtaining high-quality perovskite films with smaller grain sizes. Moreover, the coordination of CEPPA with Pb atoms on the surface of perovskite can effectively reduce film defects and thus improve the efficiency of radiation recombination. The functional molecule double rivet strategy is beneficial to the preparation of high-performance 3D perovskite LEDs with peak external quantum efficiencies exceeding 20% and with a maximum brightness of 17795 cd m ^-2 .