All‐Inorganic Bismuth‐Based Perovskite Quantum Dots with Bright Blue Photoluminescence and Excellent Stability

Abstract

Lead halide perovskite quantum dots (QDs) possess color-tunable and narrow-band emissions and are very promising for lighting and display applications, but they suffer from lead toxicity and instability. Although lead-free Bi-based and Sn-based perovskite QDs (CsSnX3, Cs2SnX6 and (CH3NH3)3Bi2X9) have been reported, they all showed low photoluminescence quantum yield (PLQY) and poor stability. Here we report the synthesis of Cs3Bi2Br9 perovskite QDs with high PLQY and excellent stability. Via a green and facile process using ethanol as the anti-solvent, as-synthesized Cs3Bi2Br9 QDs show a blue emission at 410 nm with a PLQY up to 19.4%. The whole series of Cs3Bi2X9 (X = Cl, Br, I) QDs by mixing precursors could cover the PL emission range from 393 to 545 nm. Furthermore, Cs3Bi2Br9 QDs show excellent photostability and moisture stability due to the all-inorganic nature and the surface passivation by BiOBr, which enables the one-pot This article is protected by copyright. All rights reserved. 3 synthesis of Cs3Bi2Br9 QDs/silica composite. A lead-free perovskite white light emitting diode (W-LED) is fabricated by simply combine the composite of Cs3Bi2Br9 QDs/silica with Y3Al5O12 (YAG) phosphor. As a new member of lead-free perovskite QDs, Cs3Bi2Br9 QDs open up a new route for the fabrication of optoelectronic devices due to their excellent stability and photophysical characteristics.

Recent advances and prospects toward blue perovskite materials and light‐emitting diodes

“…Compared to all inorganic lead‐based perovskites, the stability of Pb‐free perovskites is poor because of the high solubility in polar solvents. For example, although Cs 3 Bi 2 Br 9 QDs exhibit poor stability, it can be improved by hydrolytic BiOBr through a self‐passivation strategy . Similar features were also found in Bi 3+ ‐doped Cs 2 SnCl 6 , with a BiOCl protective layer isolating moisture around the Cs 2 SnCl 6 , ensuring thermal and water stability .…”

Halide Perovskite Nanocrystals for Next‐Generation Optoelectronics

“…The Cs 2 SnI 6 PNCs, with a proposed A 2 BX 6 crystalline structure (see Figure c‐i) in different morphologies (see Figure a,b), present a slight blue‐shift of the optical spectra for the as‐prepared crystals with the increase of reaction time. PNCs based on trivalent metal cations in the B‐sites of A 3 B 2 X 9 structure (see Figure c‐ii) were first theoretically designed and then recently synthesized . Cs 3 Bi 2 X 9 PNCs (see Figure d) have an emission band in the range between 400 and 560 nm.…”

Lead‐Free Halide Perovskite Nanocrystals: Crystal Structures, Synthesis, Stabilities, and Optical Properties

“…Furthermore, Cs 3 Bi 2 Br 9 QDs presented better water stability, with only 10 % relative reduction in PL intensity after 8 h storage in the presence of water (Figure b; middle panel). To further improve stability for more viable potential applications, one‐pot encapsulation was employed to yield QDs/silica composites; white LED was then fabricated by simply placing Cs 3 Bi 2 Br 9 QDs/silica and yellow‐emissive Y 3 Al 5 O 12 (YAG) on violet‐emissive GaN chips . CIE color with the coordinates of (0.18, 0.03), (0.40, 0.57), and (0.29, 0.30) corresponding to the QD/silica, YAG, and W‐LED, respectively is shown in Figure b (right panel).…”