BaGe₂P₂ and BaGe₂As₂ pnictides as promising ferroelectric semiconductors for thin film solar cell

Ferroelectric semiconductors offer a unique route to enhance photovoltaic (PV) performance through spontaneous polarization-assisted separation of e-h pairs. In this study, we investigate BaGe₂Pn₂ (Pn = P or As) as promising candidates for thin-film solar cells using density functional theory with a hybrid functional. These pnictides exhibit spontaneous polarization, suitable optical band gaps near the Shockley-Queisser limit, and strong visible-light absorption. Calculated short-circuit current densities (J_SC) indicate that efficient solar energy conversion can be achieved with submicron film thicknesses. Furthermore, both compounds possess small electron and hole effective masses, suggesting long carrier diffusion lengths. Overall, BaGe₂Pn₂ combines ferroelectricity with favorable optoelectronic properties and minimal environmental issues. These findings position BaGe₂Pn₂ as compelling ferroelectric semiconductors for high-efficiency, thin-film PV applications.