Identifying A/B-Site Effects and Screening of β-ABO₂ Ferroelectrics toward Optoelectronic Functionality

Wurtzite-derived ternary oxides are pivotal in optoelectronics owing to their widely tunable band gaps and strong spontaneous polarization. Here, through density functional theory (DFT) calculations, we establish an integrated workflow from material design to functional validation for a compositional space of 144 β-ABO₂ ferroelectrics. The synergistic effect of monovalent A-site cations and rare-earth B-site ions on structural distortion is decoupled, allowing for independent analysis of their respective roles in the continuous chemical tuning of ferroelectric polarization and band structure characteristics. By coupling A/B-site attributes, we construct two robust and transferable structure-property relationship models for polarization and band gap, each achieving a high predictive accuracy (R² > 0.95). Guided by criteria including synthetic feasibility and carrier effective mass, we identify promising optoelectronic semiconductors and evaluate their key performance metrics. Two photocatalyst (PC) candidates exhibit efficient surface oxygen evolution reaction (OER) kinetics, with rate-determining-step barriers of ∼1.36 eV under illumination. In parallel, all 14 candidate transparent conductive oxides (TCOs) maintain high visible-light transparency and show carrier mobility generally exceeding 10³ cm²s^-1V^-1. This study establishes practical design guidelines for high-performance functional materials, while also identifying concrete candidates with significant application potential.