One-Dimensional Indium(III) Halide Double Perovskites

What is it about?

Low-dimensional In(III) halide perovskites have become one of the most attractive classes of light-emitting materials due to their tunable and high photoluminescence efficiency. However, their synthesis is still a challenge. Here, we report two novel Na(I)–In(III) halide double perovskite-related compounds (MA)2NaInCl6 and (MA)2NaInBr6 and their Sb3+-doped counterparts. Both compounds crystallize in one-dimensional (1D) face-sharing chain structures with a trigonal P3̅m1 symmetry. (MA)2NaInCl6 and (MA)2NaInBr6 show wide and direct band gaps of 5.3 and 3.9 eV, respectively. While both materials are nonemissive in their pristine forms, 5% Sb3+-doped (MA)2NaInCl6 and (MA)2NaInBr6 show green (555 nm) and yellow (585 nm) emission with the photoluminescence quantum yields of 13.8 and 53.6%, respectively. For (MA)2NaInBr6, a PLQY of 67.64% was achieved with 1% Sb doping. Variable-temperature PL studies and density functional theory calculations indicate that the Sb3+ ion introduces self-trapped excitonic (STE) states, which are responsible for the high-efficiency PL emission. Our findings significantly expand the scope of halide double perovskites to low-dimensional photoluminescent In(III)-based metal halide perovskites.

Featured Image

Photo by Jahanzeb Ahsan on Unsplash

Photo by Jahanzeb Ahsan on Unsplash

Why is it important?

1. Advancement in Lead-Free Perovskites Traditional perovskites, especially lead-based ones (e.g., MAPbX₃), pose toxicity and stability issues. Indium-based double perovskites offer a lead-free alternative, making them more environmentally friendly for optoelectronic applications. 2. Unique One-Dimensional (1D) Structure Lower-dimensional perovskites (1D, 2D) exhibit enhanced stability compared to 3D perovskites, which tend to degrade under moisture and light exposure. 1D perovskites show strong exciton-phonon interactions, leading to efficient self-trapped exciton (STE) emission, which is crucial for tunable photoluminescence. 3. Role of Sb³⁺ Doping Sb³⁺ doping modifies the electronic and optical properties, introducing new luminescence centers and affecting bandgap tuning. The C-band and A-band in the excitation spectrum are linked to Sb³⁺ transitions, making this system useful for designing broadband light emitters. 4. Applications in Optoelectronics This research contributes to the development of stable, lead-free luminescent materials for: Light-emitting diodes (LEDs) Photodetectors Scintillators for radiation detection Solar energy applications 5. Fundamental Understanding of Indium Halide Chemistry The study provides insights into how indium halides crystallize in 1D perovskite-like structures, helping to design new perovskite alternatives with desirable properties.

Perspectives

“

The perspective of this article likely focuses on the future directions and broader impact of one-dimensional (1D) indium(III) halide double perovskites, particularly in terms of materials design, optoelectronic applications, and fundamental photophysics. Based on similar studies, here’s a possible perspective: 1. Expanding the Scope of Lead-Free Perovskites This work contributes to the development of environmentally friendly perovskite alternatives, addressing toxicity concerns associated with Pb-based perovskites. Future research could explore other trivalent cations (e.g., Bi³⁺, Tl³⁺) or mixed-metal strategies to further optimize optical and electronic properties. 2. Tuning Optical Properties via Halide and Dopant Engineering The study highlights how Sb³⁺ doping affects the excitation spectrum and luminescence behavior, paving the way for more tunable self-trapped exciton (STE) emissions. Further studies could investigate how varying halide composition (Cl⁻, Br⁻, I⁻) and structural modifications impact luminescence efficiency and color tuning. 3. Stability and Processing for Practical Applications 1D perovskites often exhibit better structural and moisture stability compared to their 3D counterparts. The research suggests that optimizing processing techniques (e.g., thin-film deposition, surface passivation) could improve their integration into LEDs, photodetectors, and scintillators. 4. Unraveling Excitonic and Self-Trapping Mechanisms The presence of C-band and A-band excitations in Sb³⁺-doped materials suggests strong exciton-lattice interactions, which are crucial for understanding self-trapped exciton dynamics. Advanced spectroscopy (e.g., ultrafast transient absorption, temperature-dependent PL) could provide deeper insights into carrier relaxation pathways in these materials. 5. Potential for Quantum and Energy Applications Given their tunable electronic properties, these materials could be explored for: Quantum dots and nanostructures for single-photon emission. Scintillation detectors for radiation sensing. Photovoltaic absorbers if charge transport can be optimized.

”