A zero-dimensional hybrid lead perovskite with highly efficient blue-violet light emission

Abstract

Pursuits of high-performance blue light-emitting perovskites have attracted intensive attention due to an insufficient photo-luminescence quantum yield (PLQY) of <5% for CsPbCl₃, which far lags behind the near-unit PLQYs (>90%) in the green and red emission spectral regions of CsPbX₃ (X = Br and I), respectively. Hence, it is very significant to improve the blue light emitting PLQYs to balance the development of three-primary-colour in high-definition displays. In this study, we have proposed a new structural design strategy of reducing the lattice dimension to enhance quantum confinement effect and further improve the blue-light emission efficiency. Herein, by rationally choosing a long chain-like organic cation to slice the [PbCl₃]⁻ skeleton, we have successfully constructed the first 0D perovskite of [BAPrEDA]PbCl₆·(H₂O)₂, in which the isolated [PbCl₆]⁴⁻ units are confined by a closely assembled organic matrix. As expected, the bulk crystals of the 0D perovskite display broadband blue-violet light emission (392 nm) of radiative transition arising from triplet exciton states. Remarkably, the synergistic effects of enhanced quantum confinement and highly localized excitons from the 0D perovskite significantly boost the PLQY of blue light emission to 21.3%, which far exceeds than that of the typical 3D CsPbCl₃. To the best of our knowledge, this study first realizes the lowest-dimensional structural transformation from 3D perovskite to 0D molecule but holding the intrinsic blue light emission, and it also represents a new record of highest-energy blue-violet light emission in single-crystalline 0D metal halides.