Highly Efficient Blue‐Emitting CsPbBr₃ Perovskite Nanocrystals through Neodymium Doping

Abstract

Colloidal CsPbX 3 (X = Br, Cl, and I) perovskite nanocrystals exhibit tunable bandgaps over the entire visible spectrum and high photoluminescence quantum yields in the green and red regions. However, the lack of highly efficient blue-emitting perovskite nanocrystals limits their development for optoelectronic applications. Herein, neodymium (III) (Nd 3+) doped CsPbBr 3 nanocrystals are prepared through the ligand-assisted reprecipitation method at room temperature with tunable photoemission from green to deep blue. A blue-emitting nanocrystal with a central wavelength at 459 nm, an exceptionally high photoluminescence quantum yield of 90%, and a spectral width of 19 nm is achieved. First principles calculations reveal that the increase in photoluminescence quantum yield upon doping is driven by an enhancement of the exciton binding energy due to increased electron and hole effective masses and an increase in oscillator strength due to shortening of the Pb-Br bond. Putting these results together, an all-perovskite white light-emitting diode is successfully fabricated, demonstrating that B-site composition engineering is a reliable strategy to further exploit the perovskite family for wider optoelectronic applications.

Advances in metal halide perovskite lasers: synthetic strategies, morphology control, and lasing emission

“…Most recently, there have been much more researches about perovskite QDs by composition engineering for wider optoelectronic applications. [68][69][70]…”

Recent Advances on Cyan‐Emitting (480 ≤ λ ≤ 520 nm) Metal Halide Perovskite Materials

“…Their polyvalent states endow themselves with intriguing redox properties and unique luminous and electromagnetic characteristics. [ 41–45 ]…”

“…This is due to the following reasons: 1) the reduction of (lead or halogen) defects is attributed to the flexible redox properties of REE ion pairs (e.g., Eu 3+ –Eu 2+ ), [ 42 ] 2) the enhancement of the exciton binding energy resulting from the increased electron and hole effective masses, and 3) the increase in oscillator strength ascribed to the shortening of the Pb‐halogen bond. Xie et al [ 41 ] reported the preparation of CsPbBr 3 : x Nd 3+ NCs (where x is the atomic‐doping ratio x = Nd/(Nd + Pb)) by integrating Nd 3+ into CsPbBr 3 NCs as B‐site dopants. As shown in Figure a‐i, the emission peaks could be finely tuned from blue (459 nm) to cyan (484, 494, and 515 nm, Table 1 ) with the PLQY values in the range of 75–90% through Nd 3+ doping.…”

“…Reproduced under the terms of the CC-BY 4.0 license. [ 41 ] Copyright 2020, The Authors, published by Wiley‐VCH. b) Ce 3+ ‐doped CsPbBr 3 perovskite materials.…”

“…a) PLQY comparison of the typical perovskite light‐emitting materials. b) EQE comparison of the typical PeLEDs performance (the same colors of spheres/pentagrams and captions represent the results collected from the same reference; also, data shown in this figure are collected from the representative research works, respectively [ 16,18–23,41,63,72–80 ] ).…”