The development of stable, non-toxic, and high-efficiency perovskite materials is critical for advancing next-generation photovoltaic technologies. While numerous halide double perovskites have been explored, many suffer from indirect band gaps or limited optoelectronic tunability. In this work, we employ first principles calculations to investigate the structural, electronic, and optical characteristics of the rubidium-based double perovskite Rb₂NaTlBr₆. Our results reveal that the compound exhibits a direct band gap of 1.869 eV, along with strong, dynamic and thermodynamic stability. Notably, the application of tensile strain engineering systematically reduces the band gap to 1.374 eV, placing it within the optimal range for solar absorption and significantly enhancing its optoelectronic response. The material also demonstrates high absorption coefficients and favorable carrier effective masses. Importantly, the spectroscopic limited maximum efficiency (SLME) reaches 33% under 5% tensile strain, underscoring its photovoltaic potential. The findings suggest that strain engineered Rb₂NaTlBr₆ is promising, lead-free candidate for high-efficiency solar energy applications.

The development of novel anode materials with superior electrochemical performance is imperative for advancing next-generation high-performance rechargeable batteries beyond current limitations. In this study, it presents a 2D o-Al₂C₂ monolayer as a promising lightweight candidate for lithium and sodium–ion battery systems, based on the density functional theory investigations and ab initio molecular dynamics (AIMD) simulations. Our comprehensive investigation demonstrates that the o-Al₂C₂ monolayer exhibits remarkable stability with a cohesive energy of −5.30 eV atom⁻¹ and maintains its structural integrity at room temperature during extended AIMD simulations. The o-Al₂C₂ monolayer demonstrates exceptional electrochemical characteristics for Li and Na storage: theoretical specific capacities of 3780.42 and 3436.75 mA h g⁻¹, optimal average open circuit voltages of 0.81 and 0.67 V, and favorable diffusion barriers of 0.62 eV and 0.31 eV, respectively. These performance metrics significantly surpass those of conventional graphite (372 mA h g⁻¹) and other recently reported 2D anode materials, establishing o-Al₂C₂ as an exceptionally promising candidate for next-generation energy storage applications. Hence, this current theoretical investigation suggests that the o-Al₂C₂ monolayer holds significant potential for future experimental studies in lithium and sodium storage applications for LIB and NIB systems.