Lead‐Free All‐Inorganic Indium Chloride Perovskite Variant Nanocrystals for Efficient Luminescence

Abstract

Lead‐free halide perovskites and their variants have attracted great attention due to their non‐toxicity and good photophysical properties. Here, a series of undoped and antimony‐doped all‐inorganic, 0D, indium‐based perovskite variant nanocrystals (NCs): (RbxCs1−x)3InCl6 and (RbxCs1−x)3InCl6:Sb (0 ≤ x ≤ 1) NCs, is reported. Among them, Sb‐doped NCs exhibit green emission. Mixing Rb‐Cs NCs show the higher photoluminescence (PL) quantum efficiency (PLQE) and better stability than unalloyed NCs (x = 0 or 1). The effect of crystal size on PL property of (Rb0.75Cs0.25)3InCl6:Sb is analyzed in detail. More interestingly, In‐based perovskite variant NCs containing coordinated water are successfully synthesized by a two‐step method (variable temperature hot injection and saturated steam post treatment). The best PLQE of Sb‐doped Cs2InCl5(H2O) NCs reaches 95.5%, which is a new PLQE record for yellow emissive lead‐free perovskite and variant NCs. In addition, the emission mechanism is further clarified by temperature‐dependent PL and femtosecond transient absorption techniques.

Investigation of the Solution Chemistry of Hybrid Organic–Inorganic Indium Halides for New Material Discovery

“…The obtained results on the MA–In–Br system are discussed together with strategies for further novel material discovery and solution chemistry work in other homometallic and heterometallic halide systems. Note that several new indium­(III) halides have recently been reported as efficient optical materials; − thus, this study further expands the indium halide family for luminescence applications.…”

“…Plots of the diffuse reflectance data against photon energy gives estimated band gap energy values of 3.77, 3.54, and 3.69 eV for MAInBr 4 , MA 2 InBr 5 , and MA 4 InBr 7 , respectively. In literature, all-inorganic and hybrid organic–inorganic indium halides have been studied as prospective high-efficiency light emitters, − however, MAInBr 4 , MA 2 InBr 5 , and MA 4 InBr 7 exhibit very weak, essentially quenched photoluminescence (PL), spectra.…”

Lead-free broadband orange-emitting zero-dimensional Sb3+-doped indium-based organic–inorganic metal halides

“…According to the above equation, the activation energy of the as-prepared Sb 3+ -doped (CH 3 NH 3 ) 4 ClInCl 6 is 590.8 meV; the relatively large activation energy is higher than those of Cu-based or Bi-based metal halides. 51,52 The correlation between half peak width and temperature and the degree of electron phonon coupling can be evaluated through the equation: 53–55 …”

Pivotal Role of A-Site Cations in Tailoring the Band-Edge States, Optical Properties, and Stability of 0D Hybrid Indium Chlorides

“…Although the magnitude of the red-shift is small, it systematically increases with the increase in the number of methyl groups on the A-site cation. The transitions corresponding to these absorption maxima are primarily localized on inorganic octahedra [InCl 6 ] 3– . Therefore, the shift in the peak position indicates subtle changes in the position of VB and CB and might be resulting from structural changes with changes in the A-site cation.…”

“…The transitions corresponding to these absorption maxima are primarily localized on inorganic octahedra [InCl 6 ] 3− . 50 Therefore, the shift in the peak position indicates subtle changes in the position of VB and CB and might be resulting from structural changes with changes in the A-site cation.…”