In Situ Halide Vacancy Tuning of Low-Dimensional Lead Perovskites to Realize Multiple Adjustable Luminescence Performance.

Surface defects play a crucial role in the photophysical properties and optoelectronic applications of perovskite materials. Although luminescent efficiency is improved through post-synthetic defect passivation, comprehensive optimization of photoluminescent performance via defect chemistry remains a significant challenge. Herein, a successful defect engineering strategy is demonstrated toward 0D perovskite of [DADPA]PbBr(5) (DADPA = diaminodipropylamine) single crystal to achieve multiple adjustable luminescent properties. Through fine-tuning the crystallization environment to diminish Br vacancy (V(Br)), [DADPA]PbBr(5) displays gradually evolutionary luminescence range from broadband blue-white to narrow green light emissions, with continuously adjustable dominant wavelengths (445-535 nm) and linewidths (134-27 nm). Meanwhile, the quantum yields increase significantly from 3.7% to 80.8%, and lifetime extends from 5.4 to 57.7 ns. This is the pioneering discovery in perovskite chemistry for simultaneous modification of multi-dimensional luminescent performances. Combined spectroscopic investigations and first-principles calculations indicate that the reducing V(Br) significantly narrows the bandgap and inhibits nonradiative recombination, which attenuates interband trap-state-associated broadband emission and facilitates the formation of bound exciton for enhanced emission efficiency. More remarkably, this universal strategy can be extended to other perovskite systems with similar luminescent adjustability, paving the way for applications of diverse perovskites with improved optoelectronic performance.