The optoelectronic properties of lead-free Cs₂NaBiI₆ double perovskites via Mg²⁺ doping

Abstract

This study analyzes the structural and optical properties of Mg2+-doped Cs2NaBiI6, synthesized through hydrothermal methods, paying special attention to magnesium additions. The nominal magnesium doping levels of 1%, 3%, and 5% were used. These were characterized using X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy (TEM), and UV-Vis absorption spectroscopy. The results showed that the incorporation of Mg2+ ions improved crystallization processes by decreasing the energy band gap and increasing light absorption, especially at the 3% and 5% ratios, which also had a more dense and uniform structure. Furthermore, XRD analyses confirmed that the main crystalline phase was unchanged with only some evidence of secondary phase formation at the highest percent of blur. The findings indicate that the post incorporation of magnesium ion on Cs2NaBiI6 may enhance its efficiency as a potential photovoltaic sorbent, especially for solar cells due to its low environmental impact.