Efficient White Photoluminescence from Self-Trapped Excitons in Sb³⁺/Bi³⁺-Codoped Cs₂NaInCl₆ Double Perovskites with Tunable Dual-Emission

Abstract

Efficient and stable inorganic lead-free halide perovskites have attracted tremendous attention for next-generation solid-state lighting. However, single perovskite phosphors with strong, tunablecolor-temperature white-light emission are rare. Here, a doping strategy was developed to incorporate Sb 3+ and Bi 3+ ions into Cs 2 NaInCl 6 single crystals. Blue and yellow emission for white light with a 77% quantum yield was observed. The dual-emission originates from different [SbCl 6 ] 3− octahedron-related self-trapped excitons (STEs). The blue emission is attributable to limited Jahn−Teller deformation from Sb 3+ doping. Largeradii Bi 3+ increase the deformation level of the [SbCl 6 ] 3− octahedron, enhancing yellow STE emission. Density functional theory calculations indicated that the Bi 3+ doping forms a sub-band level, which produces yellow STE emission. Tuning between warm and cold white light can be realized by changing the Sb 3+ /Bi 3+ doping ratio, which suggests a unique interaction mechanism between Sb 3+ and Bi 3+ dopants, as well as Bi 3+ -induced lattice distortion in double perovskites.

Highly Reversible Moisture‐Induced Bright Self‐Trapped Exciton Emissions in a Copper‐Based Organic–Inorganic Hybrid Metal Halide

“…The absorption spectrum had a single absorption peak at 300–400 nm, overlapping with the edge of the excitation spectrum, which is more commonly observed in materials with strong self‐trapped excitons emissions. [ 8 ] To reveal the excitonic behaviors, the time‐resolved PL decay spectrum was measured at an emission wavelength of 520 nm under an excitation wavelength of 345 nm. As shown in Figure 1f, the PL decay spectra was fitted by a single exponential decay function.…”

“…[ 6 ] However, lead halide perovskites are unstable and toxic, which limits their practical applications. Lead‐free metal halide perovskites (such as Sn‐, Ge‐, Bi‐, In‐based perovskites) have lower toxicity, [ 7,8 ] but their stability is still unsatisfactory. [ 9 ] This instability includes structural changes and decomposition in response to factors such as water, radiation, and heat.…”

“…[ 23 ] Interestingly, due to the strong electron‐phonon coupling effect, the exciton emission in perovskite‐related materials could be flexibly tuned by various approaches (such as chemical doping, external forces, organic ligand and etc.). [ 8,24 ] Therefore, it would be possible to realize moisture‐activated luminescence in perovskite‐related materials, once water molecules have a desirable interaction with the crystalline structure of the material, in which improved PL stability in the air, and even conversion from a non‐emissive state to strong fluorescent state can be expected.…”

Compact ultrabroadband light-emitting diodes based on lanthanide-doped lead-free double perovskites

“…Unfortunately, their use of toxic lead and their poor stability to heat, water, electric fields, and light hamper their commercialization and industrialization on a large scale 22 , 23 . As an alternative, lead-free halide double perovskites (DP S ) have drawn extensive attention for their fascinating optical performance and excellent stability 24 – 26 . Among the DP family, Cs 2 AgInCl 6 has been in the spotlight for its direct bandgap characteristics and various alloy compositions with mono- and trivalent cations other than Ag + and In 3+ 27 – 29 .…”

Engineering of Annealing and Surface Passivation toward Efficient and Stable Quasi-2D Perovskite Light-Emitting Diodes

“…Lead halide perovskites have received extensive attention in the field of light-emitting diodes (LEDs) due to their efficient radiative recombination, wide luminous color gamut, and high color purity. − The quasi-two-dimensional (quasi-2D) perovskite with a self-assembled multiple quantum wells (QWs) structure proves to be one of the great light emitters, which possesses high exciton binding energy ( E b ) and an efficient energy-funnel effect that appealing to application in perovskite light-emitting diodes (PeLEDs) and lasers. − The PeLEDs based on quasi-2D perovskites have obtained remarkable external quantum efficiencies (EQEs) of >20% for green and red PeLEDs and 10% for blue devices. − Meanwhile, the efficient quasi-2D perovskite emitters can be prepared by simple one-step solution processing and demonstrate great potential for low-cost and flexible lighting and display. During solution processing, thermal annealing is an indispensable procedure in the preparation of perovskite films to remove residual solvent and promote crystallization.…”