A Systematic Quantum Analysis to Explore Essential Physical Properties of Lanthanum Germanate Structure for Next‐Generation Photovoltaic Applications: A Density Functional Theory Study

ABSTRACT The pyrochlore La 2 Ge 2 O 7 is a promising compound for renewable energy applications due to its tunable optoelectronic, mechanical, and thermodynamic aspects under applied pressure from 0–100 GPa. In this research study, we employed density functional theory (DFT) to thoroughly investigate its fundamental properties and evaluate its potential for renewable energy applications. Our result findings specify that La 2 Ge 2 O 7 retains a cubic phase. The powder X‐ray diffraction reveals a shift of diffraction peaks to higher angles under compression, which is mainly ascribed to lattice contraction and modifications in crystallographic parameters. The calculated direct band gap values are 1.13, 1.79, 1.90, and 2.50 eV for 0, 40, 60, and 100 GPa, respectively. The elastic and mechanical properties confirm its structural stability, mechanical robustness, and ductility, which are essential for high‐pressure applications. The SCAPS‐1D simulation results illustrate that the device architecture comprising FTO/PCBM/La 2 Ge 2 O 7 /CuI/Au exhibits outstanding performance, with an open circuit voltage of 0.8011 V, a short circuit density of 39.53 mA/cm 2 , a fill factor of 80.76%, and a power conversion efficiency of 25.57%. These obtained findings offer a comprehensive and detailed understanding of thermodynamically stable La 2 Ge 2 O 7 material and highlight its potential as a multi‐functional substance for next‐generation renewable energy applications and sustainable solar cell energy solutions.