A Highly Red‐Emissive Lead‐Free Indium‐Based Perovskite Single Crystal for Sensitive Water Detection

Abstract

Low‐dimensional luminescent lead halide perovskites have attracted tremendous attention for their fascinating optoelectronic properties, while the toxicity of lead is still considered a drawback. Herein, we report a novel lead‐free zero‐dimensional (0D) indium‐based perovskite (Cs2InBr5⋅H2O) single crystal that is red‐luminescent with a high photoluminescence quantum yield (PLQY) of 33 %. Experimental and computational studies reveal that the strong PL emission might originate from self‐trapping excitons (STEs) that result from an excited‐state structural deformation. More importantly, the in situ transformation between hydrated Cs2InBr5⋅H2O and the dehydrated form is accompanied with a switchable dual emission, which enables it to act as a PL water‐sensor in humidity detection or the detection of traces of water in organic solvents.

Water‐Mediated Synthesis of a Superionic Halide Solid Electrolyte

“…The corresponding X‐ray diffraction (XRD) patterns were not matched to any particular chemicals including LiCl, InCl 3 , InCl 3 ⋅ x H 2 O, and Li 3 InCl 6 . The obtained product was probably a hydrated form of lithium indium chloride as Li 3 InCl 6 ⋅ x H 2 O similar to other indium halide hydrates, such as Cs 2 InBr 5 ⋅H 2 O, (NH 4 ) 2 InCl 5 ⋅H 2 O and K 3 InCl 6 ⋅ n H 2 O . Coordinating water was confirmed by Fourier transform infrared spectroscopy (Figure S2).…”

Intrinsic Self‐Trapped Emission in 0D Lead‐Free (C4H14N2)2In2Br10 Single Crystal

“…[15] Thep rojected density of states (DOS;F igure 3b)s hows that the HOMOs mainly consist of Br 4p orbitals,a nd the lowest unoccupied molecular orbitals (LUMOs) are composed of Br 4p and In 5s orbitals.A ccording to our previous work, the In-Br octahedrons in perovskite material are prone to structural distortion upon photoexcitation, which lay the foundation for broadband emission. [16] Considering [InBr 6 ] 3À octahedrons and [InBr 4 ] À tetrahedrons concurrently exist, the geometries variation of (C 4 H 14 N 2 ) 2 In 2 Br 10 after light stimulation has been unveiled to distinguish their respective contributions to the optical and electrical properties of (C 4 H 14 N 2 ) 2 In 2 Br 10 (Figure 3c,d). Obviously,asignificant structural deformation is found in [InBr 6 ] 3À octahedrons when transforming from the optimized underground state to the excited state.Specifically,the In À Br bond lengths and Br-In-Br bond angles are largely elongated and changed, respectively (see details in the Supporting Information, Tables S2 and S3).…”

An Organic Crystal with High Elasticity at an Ultra‐Low Temperature (77 K) and Shapeability at High Temperatures

“…Organic single crystals have attracted ag reat deal of research interest as functional materials,i ncluding the active materials for optoelectronic applications (such as organic light-emitting diodes, [1,2] field-effect transistors [3,4] and optical waveguides [5,6] ), as well as responsive materials for light, [7,8] heat, [9,10] pressure/grinding [11,12] and solvent vapors. [13,14] Recently,o rganic crystals with elasticity,w hich break the traditional thinking that organic crystals are hard and brittle, have been known, and more and more elastic organic single crystals (EOSCs) have been reported. [15][16][17][18][19][20][21][22] Besides the interesting elastic phenomenon itself,p otential applications of EOSCs in flexible devices and sensors were the driving force for related studies.…”