Tuning of bandgap for warm white light emissions in indium-doped cesium metal halide perovskites by solvothermal method

• Potential for Energy-Efficiency: Demonstrated the potential of Cs3Bi2Br9 perovskites doped with varying Indium concentrations for energy-saving lighting technologies, particularly in Warm White Light Emitting Diodes (WLEDs). • Enhanced Stability: Indium doping led to significant alterations in the optical properties of perovskites while enhancing their stability, making them suitable for long-term use. • Tunable Bandgap: Successfully achieved the essential requirements for WLEDs, including a tunable bandgap, and efficient photon emission, resulting in the production of bluish-white light using these materials. • Environmentally Friendl y : These metal halide perovskites are lead-free and rare-earth-free, presenting promising prospects for future lighting applications that contribute to the sustainability of the environment and energy conservation. Cesium-based perovskites, particularly Cs 3 Bi 2 Br 9 , doped with indium, have emerged as promising materials for energy-efficient lighting, notably in white light-emitting diodes (WLEDs). This study aimed to address environmental concerns associated with lighting technology by employing solvothermal synthesis to fabricate these materials. Comprehensive characterization techniques, including X-ray diffraction (XRD), transmission electron microscopy (TEM), and photoluminescence spectroscopy (PL), were applied to assess their properties. XRD analysis confirmed the formation of Cs 3 Bi 2 Br 9 with a trigonal crystal structure and indium doping induced significant changes in the material’s color and crystal lattice. TEM imaging, even after six months, revealed the presence of stable nanocrystals, indicating the material’s durability in practical applications. UV–Vis absorption and photoluminescence spectroscopy showed variable bandgaps and efficient photon emission. Notably, as the indium doping concentration increased, the emitted light shifted from blue to bluish-white, making these materials highly suitable for the synthesis of WLEDs. This research offers a promising prospect to address environmental issues associated with lighting technology while advancing energy-efficient illumination solutions.