Lead-free halide double perovskites continue to draw increasing attention in view of their nontoxicity and stability compared to lead-based perovskites. Herein, we optimized the colloidal synthesis of undoped and Bi-doped Cs2AgInCl6 nanocrystals (NCs) via the facile hot-injection process using nontoxic and available precursors. The synthesis conditions including temperature, ligands, and hydrochloric acid are investigated to boost the photoluminescence quantum yield (PLQY) of Cs2AgInCl6:Bi NCs with the trace amount of Bi doping. The broad-band orange emission peaking at 580 nm is observed with the PLQY as high as ∼11.4%, and the related luminescence mechanism has been discussed. This work provides a reliable avenue toward the optimization of optical properties for emerging lead-free halide perovskite NCs with enhanced PLQY.

Doped halide perovskite nanocrystals (NCs) have opened new opportunities for the emerging optical and optoelectronic applications. Here, we describe a hot-injection synthesis of all-inorganic lead-free Cs 2 SnCl 6 and Sb 3+ doped Cs 2 SnCl 6 NCs. Cs 2 SnCl 6 NCs present a blue emission peak at 438 nm, whereas a new broad-band emission peak appears at 615 nm for the Sb 3+ doped NCs. Comparative structural and spectral characterizations of Sb 3+ doped Cs 2 SnCl 6 NCs with micrometersized undoped and Sb 3+ doped crystals show that the formation of broad-band orange emission is originted from triplet self-trapped excitons, attributed to the 3 P n − 1 S 0 transitions (n = 0, 1, 2). Our results in Sb 3+ doped Cs 2 SnCl 6 materials provide insights into the machanisms of doping-induced emission centers, and it extends the existing knowledge of optical properties of doped halide NCs for further studies.

The incorporation of impurity ions or doping is a promising method for controlling the electronic and optical properties and the structural stability of halide perovskite nanocrystals (NCs). Herein, we establish relationships between rare‐earth ions doping and intrinsic emission of lead‐free double perovskite Cs2AgInCl6 NCs to impart and tune the optical performances in the visible light region. Tb3+ ions were incorporated into Cs2AgInCl6 NCs and occupied In3+ sites as verified by both crystallographic analyses and first‐principles calculations. Trace amounts of Bi doping endowed the characteristic emission (5D4→7F6‐3) of Tb3+ ions with a new excitation peak at 368 nm rather than the single characteristic excitation at 290 nm of Tb3+. By controlling Tb3+ ions concentration, the emission colors of Bi‐doped Cs2Ag(In1−xTbx)Cl6 NCs could be continuously tuned from green to orange, through the efficient energy‐transfer channel from self‐trapped excitons to Tb3+ ions. Our study provides the salient features of the material design of lead‐free perovskite NCs and to expand their luminescence applications.

We report electron-doped AgBiS as a new high-performance nontoxic thermoelectric material. This compound features exceptionally low lattice thermal conductivities of 0.5-0.3 W m K in the temperature range of 300-800 K, which is ascribed to its unusual vibrational properties: "double rattling" phonon modes associated with Ag and Bi atoms. Chlorine doping at anion sites acts as an efficient electron donor, significantly enhancing the electrical properties of AgBiS. In the carrier concentration range (5 × 10-2 × 10 cm) investigated in this study, the trends in Seebeck coefficient can be reasonably understood using a single parabolic band model with the electron effective mass of 0.22 m (m is the free electron mass). Samples of 0.33% Cl-doped AgBiS prepared by spark plasma sintering show a thermoelectric figure of merit of ∼1.0 at 800 K.

Finding new low-dimensional metal halides with broad-band emission is attracting interest in single-component phosphor for white light-emitting diodes (WLEDs). The full-spectrum white light still remains a challenge as found in the two-dimensional hybrid material (C6H18N2O2)­PbBr4 exhibiting the intrinsic free exciton (FE) and broad-band self-trap exciton (STE) emission upon 365 nm ultraviolet excitation, and a combined strategy has been proposed through doping the Mn2+ ions enabling a superposition of multiple emission centers toward the ultra-broad-band warm white light. The occupation of Mn2+ in (C6H18N2O2)­PbBr4 has been discussed, and optical investigations verify that the warm white-light emission of Mn2+-doped (C6H18N2O2)­PbBr4 originates from the coupling effects of the FE, STEs, and the 4T1–6A1 transition of the doped Mn2+. When the concentration of Mn2+ is 5%, the emission spectrum of the phosphor covers all visible-light areas with a full width at half maximum (FWHM) of about 230 nm. The high R a (84.9) and warm light CCT (3577 K) values of the as-fabricated WLED lamp demonstrate that (C6H18N2O2)­Pb1–x Mn x Br4 can be promising as single-component white-light phosphor in solid-state lighting. Our work could provide a new understanding and perspective about hybrid metal halides for designing superior phosphor toward single-component white emission.