Deep‐Blue Electroluminescence of Perovskites with Reduced Dimensionality Achieved by Manipulating Adsorption‐Energy Differences

The lagging development of deep‐blue perovskite light‐emitting diodes (PeLEDs) heavily impedes their practical applications in full‐color display due to the absence of spectrally stable emitters and the mismatch of carrier injection capacity. Herein, we report highly efficient deep‐blue PeLEDs through a new chemical strategy that addresses the dilemma for simultaneously constant electroluminescence (EL) spectra and high‐purify phase in reduced‐dimensional perovskites. The success lies in the control of adsorption‐energy differences between phenylbutylamine (PBA) and ethylamine (EA) interacting with perovskites, which facilitates narrow n‐value distribution. This approach leads to an increased exciton binding energy and enhanced surface potential, hence improving radiative recombination. As a result, an external quantum efficiency of 4.62 % is achieved in PeLEDs with a stable EL peak at 457 nm, demonstrating the best reported result for deep‐blue PeLEDs so far. In this work, we have exemplified the critical role of adsorption‐energy differences in the structural regulation of reduced‐dimensional perovskites by complementing theoretical calculations and experiments. As a result, we achieved deep‐blue PeLED peaking at 457 nm with a record EQE of 4.62 % accompanied by stable electroluminescent spectra. Our findings provide a way for PeLEDs to develop their full technological potential.