Synthesis, Structural, Morphological, and Optical Properties of Promising Lead-Free Double Perovskite Na₂CuBiBr₆: A Sustainable Material for Photovoltaic Applications

This work primarily focuses on synthesizing and evaluating the structure, morphology, and optical features of double perovskite Na₂CuBiBr₆ for photovoltaic devices. In the present investigation, Na₂CuBiBr₆ is created by a solution-based antisolvent recrystallization approach. A comprehensive experimental investigation is conducted on the Na₂CuBiBr₆ double perovskite, encompassing its structural configuration, morphology, and optical features. X-ray diffraction analysis verifies the creation of Na₂CuBiBr₆ double perovskite and showcases its exceptional phase stability in the cubic phase. Scanning electron microscopy reveals the presence of multidirectional crystals of Na₂CuBiBr₆ crystals. The presence of polycrystalline cubic Na₂CuBiBr₆ is confirmed using transmission electron microscopy and electron diffraction investigation. In addition, energy-dispersive X-ray spectroscopy demonstrates the consistent distribution of elements within Na₂CuBiBr₆. UV–vis spectroscopy reveals a band gap of 1.37 eV. The optical characteristics demonstrate that Na₂CuBiBr₆ exhibits a greater absorbance level and a lower reflectivity level within the visible spectrum. The results of this study suggest that the Na₂CuBiBr₆ double perovskite, which is both lead-free and environmentally benign, has significant potential for applications in photovoltaic and thermoelectric devices.