University of Oxford researchers discover efficient solar semiconductor

A research team led by the University of Oxford has identified a novel compound semiconductor, bismuth sulphide (Bi2S3), that could significantly improve solar panel efficiency. The study, published in Nature, addresses a long-standing challenge in solar energy: materials that absorb light strongly often lose electrical charges too quickly to generate efficient power.

Researchers discovered that bismuth sulphide acts as a pseudo-direct semiconductor. This unique electronic structure allows the material to absorb sunlight strongly while utilizing a secondary energy state that acts as a temporary holding tank for captured charges. This mechanism reduces charge loss by approximately 75% at room temperature by slowing down the recombination process.

The team utilized ultrafast terahertz spectroscopy, employing extremely short laser pulses to measure how quickly charges disappeared in thin films of the material. This discovery suggests that the trade-off between light absorption and charge retention is not inevitable, providing a new principle for designing more effective solar cells.