Lead‐Free Perovskite Variant Solid Solutions Cs₂Sn_1–xTe_xCl₆: Bright Luminescence and High Anti‐Water Stability

Abstract

Underwater lighting is important for the exploration of the underwater world in different areas. It is of great significance for developing underwater emitters with high penetrability, high luminous efficiency, good anti‐water stability, and environmental friendliness. Stable lead‐free perovskite luminescent materials, represented by vacancy‐ordered double perovskites, are worthy of research because they can almost meet the above requirements. Here, lead‐free perovskite variant solid solutions with the formula of Cs2Sn1−xTexCl6 are reported. Upon the exchange of Sn/Te ions, strong Jahn–Teller distortion of octahedra occurs in the lattice structure. The combination of Te luminescent center and Jahn–Teller‐like self‐trapped excitons gives this material yellow‐green luminescence with a wavelength of 580 nm and a high photoluminescence quantum yield of 95.4%. Moreover, these solid solutions can withstand the extreme conditions of immersion in water probably due to the formation of amorphous alteration phase. Such good anti‐water stability is also supported by the molecule dynamics simulation result that no reaction occurs on the water/Cs2SnCl6 interface. The high luminous, suitable wavelength, and good anti‐water stability enable the solid solutions suitable for the application for underwater lighting.

Halide Perovskite Nanocrystal Emitters

“…[ 159,212–222 ] The lead‐free counterparts include copper halides (Cs 3 Cu 2 I 5, Rb 2 CuX 3 , K 2 CuX 3 , X = Br, Cl), CsSnX 3 (X = I, Br), Cs 3 Sb 2 Br 9 , FA 3 Bi 2 Br 9, (OCTAm) 2 SnBr 4, PEA 2 SnI 4 , CH 3 NH 3 Sn(Br 1− x I x ) 3 , vacancy‐ordered halide double perovskites (Bi‐Cs 2 SnI 6 , Cs 2 Sn 1− x Te x Cl 6 ), and halide double perovskites (Cs 2 Ag x Na 1− x InCl 6, Cs 2 AgInCl 6 , Cs 2 AgBiBr 6 ), (C 4 N 2 H 14 Br) 4 SnBr 6 , which display near unity PLQYs. [ 159,212–227 ] The Cs 3 Cu 2 I 5 ‐based LED has shown a low EQE of 1.1% and exhibited a high operational time (109 h). [ 159 ] The maximum EQE of 5% was demonstrated for PEA 2 SnI 4 ‐based LEDs made with valeric acid (VA), and they have also shown an operating time of 15 h. [ 225 ] The position of EL spectra does not change even after 9 h operation.…”

“…[ 159,212–222 ] The large tolerance on exciton binding energies, bandgaps, and charge‐carrier mobility of the materials have a critical role in obtaining high device performance. [ 159,212–222 ] A combination of experimental and theoretical investigations on exciton binding energies, bandgaps, and charge‐carrier mobilities may help to search for the suitable lead‐free materials for high‐performance LEDs. [ 159,212–222 ]…”

“…[ 159,212–222 ] A combination of experimental and theoretical investigations on exciton binding energies, bandgaps, and charge‐carrier mobilities may help to search for the suitable lead‐free materials for high‐performance LEDs. [ 159,212–222 ]…”

Solvatochromic Photoluminescent Effects in All‐Inorganic Manganese(II)‐Based Perovskites by Highly Selective Solvent‐Induced Crystal‐to‐Crystal Phase Transformations

“…The double‐perovskite structure Cs 2 B + B 3+ X 6 (B + =Ag + , Na + ; B 3+ =Bi 3+ , In 3+ , Sb 3+ ; X=Cl, Br, I) nanocrystals and single crystals have also been extensively explored from preparation method, quantum efficiency improvement, band gap regulation, theoretical calculation and other studies on photoelectric properties to applications in X‐ray or photoelectric detection [15–27] . Others, such as indium‐based, [28–30] copper‐based, [31–33] and tellurium‐based [34–36] low‐dimensional perovskite materials also present some fascinating photoelectric properties, for example, the unique sensitive to humidity or X‐ray and the intrinsic or extrinsic self‐trapped excitons (STEs) which contribute to broad emission and high quantum yield.…”

Lead‐Free Halide Double Perovskite Nanocrystals for Light‐Emitting Applications: Strategies for Boosting Efficiency and Stability

“…Lead‐free HDP nanocrystals have been documented wide application prospects in solar cells, [ 53–57 ] LEDs, [ 58 ] photocatalysis, [ 59,60 ] photodetectors, [ 61 ] and many other optoelectronic fields. [ 62,63 ] Although Sn 4+ ‐based, [ 64–67 ] Zr 4+ ‐based, [ 68 ] Na + /Bi 3+ ‐based, [ 69,70 ] Na + /In 3+ ‐based, [ 71 ] K + /In 3+ ‐based, [ 71 ] Ag + /In 3+ ‐based, [ 72–77 ] and Mn 2+ /Bi 3+ ‐based, [ 78,79 ] lead‐free HDP bulk materials with highly efficient emission ( Table 1 ) have been designed and synthesized in recent years, the photoluminescent (PL) properties of colloidal HDP nanocrystals still remain enormous challenge for application in LED devices compared with lead halide perovskite nanocrystals. The main reasons for poor PL performance of colloidal HDP nanocrystals can be ascribed to their intrinsic and surface defects, indirect band gaps, and forbidden transitions.…”