First-Principles and Device-Level Investigation of β-AgGaO2 Ferroelectric Semiconductors for Photovoltaic Applications

Ferroelectric semiconductors, with their inherent spontaneous polarization, present a promising approach for efficient charge separation, making them attractive for photovoltaic applications. The potential of β-AgGaO2, a polar ternary oxide with an orthorhombic Pna21 structure, as a light-absorbing material is evaluated. First-principles computational analysis reveals that β-AgGaO2 possesses an indirect bandgap of 2.1 eV and exhibits pronounced absorption within the visible spectral range. Optical simulations suggest that a 300 nm thick absorber layer could theoretically achieve a power conversion efficiency (PCE) of 20%. Device-level simulations using SCAPS-1D evaluate the influence of hole and electron transport layers on solar cell performance. Among the tested hole transport materials, Cu2FeSnS4 (CFTS) achieves the highest PCE of 14%, attributed to its optimized valence band alignment and reduced recombination losses. In contrast, no significant improvements were observed with the electron transport layers tested. These findings indicate the potential of β-AgGaO2 as a ferroelectric photovoltaic absorber and emphasize the importance of band alignment and interface engineering for optimizing device performance.