Sb3+ doping confers highly efficient and color-diverse broadband light emission to all-inorganic metal-halide perovskites. However, the emission mechanism is still under debate. Herein, a trace amount of Sb3+ ions (<0.1% atomic percentage) doping in the typical all-inorganic perovskites Cs2NaInCl6, Rb3InCl6, and Cs2InCl5·H2O allows universal observation of the fine structure in the photoluminescence excitation spectrum of the ns 2 electron. A lifetime mapping method was utilized to reveal the origin of broadband emission triggered by Sb3+ doping, by which various fluorescence components can be differentiated. In particular, free-exciton emission was identified at the high-energy end of the broadband emission for all three doped systems. The excitation-energy- and temperature-dependent fluorescence decay further indicates the existence and origin of self-trapped states. The observed structural and vibrational symmetry-dependent emission behaviors suggest dipole interactions can dramatically alter Stokes-shift energy and modulate the light-emitting wavelength.

Inorganic lead-free halide perovskites with a broadband emission of self-trapped excitons (STEs) have attracted great attention in lighting applications. However, it remains a fundamental challenge to expand the display color gamut because it is difficult to individually tune the emitting proportion at different wavelengths. Herein, we employ a doping route to incorporate Sb 3+ , Er 3+ , and Ho 3+ ions into the Cs 2 NaInCl 6 , which enables multicolor emissions with narrow full width at half-maxima and high photoluminescence quantum yields (PLQYs). The blue emission (445 nm) originates from STEs in the [SbCl 6 ] 3− octahedrons, while the narrowband green (550 nm) and red (655 nm) emissions are mainly derived from the Er 3+ and Ho 3+ ions, respectively. An efficient energy transfer between multiple luminescent centers is the key point to achieve such an efficient and tunable emission. By controlling the lanthanide doping level, the emission color can be systematically modulated, and cold 10401 K (0.278, 0.286) to warm 4608 K (0.347, 0.298) adjustable white-light emission (PLQY of ∼70%) can be achieved successfully. The results provide inspiration for the material design of lead-free perovskites with efficient and tunable light-emitting properties for optoelectronic applications.

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Realizing multicolor emissions of upconversion (UC) luminescence materials is of significant importance for information security and anticounterfeiting fields. Herein, a strategy is reported to achieve UC multicolor luminescence through manipulating the electronic transition process under dual‐wavelength excitation. The novel color can be produced via exploiting the synergistic effect of photons under dual‐wavelength excitation to control electron distribution, and can be further modulated by finely adjusting the excitation power. Furthermore, the range of color‐tunable emissions is expanded by adjusting Yb3+ ions concentrations due to the energy back transfer (EBT) process. Inspired by this, the materials with broad‐range UC multicolor emissions can be used to design high‐capacity photonic barcodes for anticounterfeiting applications, which provides a significant step for advanced anticounterfeiting of high level security.