Multiferroic oxides are promising alternatives of the perovskite light-harvesting materials (usually including Pb), because of their stable and environment-friendly characteristics. However, multiferroic oxides usually have large bandgaps, thus absorbing only a small portion of solar energy. In the present study, we discovered a giant bandgap reduction of Co₃TeO₆ (CTO) at high pressure. The high-pressure phase with small bandgap is quenchable to the ambient condition, indicating it is a potential light-harvesting material in photovoltaic applications. This study also demonstrates that high-pressure is an efficient and green technique to tune the bandgap of multifunction materials.

double perovskite,high pressure,bandgap,DAC,phase transition