Highly Efficient Blue‐Emitting Bi‐Doped Cs₂SnCl₆ Perovskite Variant: Photoluminescence Induced by Impurity Doping

Abstract

Lead halide perovskites show excellent optoelectronic properties but are unsatisfactory in terms of stability and toxicity. Herein, bismuth (Bi)‐doped lead‐free inorganic perovskites Cs2SnCl6:Bi are reported as blue emissive phosphors. Upon Bi doping, the originally nonluminous Cs2SnCl6 exhibits a highly efficient deep‐blue emission at 455 nm, with a Stokes shift of 106 nm and a high photoluminescence quantum yield (PLQY) close to 80%. Hybrid density functional theory calculations suggest the preferred formation of [BiSn+VCl] defect complex, which is believed to be responsible for the optical absorption and the associated blue emission. The Cs2SnCl6:Bi also shows impressive thermal and water stability due to its inorganic nature and the formation of protective BiOCl layer. White light‐emitting diodes (LEDs) are constructed using Cs2SnCl6:Bi and commercial yellow phosphors combined with commercial UV LED chips, giving the Commission Internationale de I'Eclairage (CIE) color coordinates of (0.36, 0.37). This work represents a significant step toward the realization of highly efficient, stable, and environmentally benign next‐generation solid‐state lighting.

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

“…This is because Bi 3+ is isoelectronic with Pb 2+ and more stable than Sn 2+ . However, Bi 3+ ‐doped Cs 2 SnCl 6 demonstrates great potential for blue perovskites . As shown in Figure D, Bi concentrations increased from 0% to 6.63%, accompanied by a bandgap reduction from 3.9 eV (Cs 2 SnCl 6 ) to about 3.0 eV (Bi 3+ ‐doped Cs 2 SnCl 6 ) due to the formation of the defect bands.…”

“…Hence, the stability and PLQY are obviously enhanced by reducing the defect state density and passivating grain boundaries, leading to excellent optoelectronic properties for devices constructed by using the doped perovskites as active layers . Typically, various metal ions, including Bi 3+ , Ni 2+ , Mn 2+ , Cu 2+ , Zn 2+ , Cd 2+ and rare earth ions (eg, Ce 3+ , Er 3+ , Yb 3+ ), have been doped into halide perovskites. In the halide perovskite system, the similar bond energy between doped elements with X and Pb‐X is considered to be one of the key factors that favors impurity incorporation …”

“…Copyright 2016, John Wiley and Sons D, UV‐vis absorption spectra of Cs 2 SnCl 6 : x Bi. Insets are the magnified absorption spectra from 325 to 425 nm and the photos of Cs 2 SnCl 6 : x Bi under 365 nm UV light illumination . Copyright 2015, John Wiley and Sons…”

Halide Perovskite Nanocrystals for Next‐Generation Optoelectronics

“…However, there is some exceptional case like Cs 2 SnCl 6 :Bi that shows high PLQY of ≈80% with long‐lived PL decay lifetime (τ avg = 343 ns). When small amounts of bismuth were incorporated into Cs 2 SnCl 6 matrix at the Sn site, it forms the so called Bi Sn + V Cl defect complex with strong blue emission . This method provides an alternative pathway to explore novel lead‐free PNC emitters.…”

Organic–inorganic metal halide hybrids beyond perovskites

“…Electronic and optical properties of semiconductors can be efficiently manipulated by doping different metal ions, such as Mn 2+ [15,16], Sn 2+ , Cd 2+ , Zn 2+ [146], Bi 3+ [147], Au 3+ [148], and various lanthanide ions (Ce 3+ , Sm 3+ , Eu 3+ , Tb 3+ , Dy 3+ , Er 3+ , and Yb 3+ ) [149]. Among all these doped metal ions, Mn 2+ has attracted the most research attention, owing to the intriguing properties of Mn-doped metal halide hybrids, e.g.…”