Defect engineering for creating and enhancing bulk photovoltaic effect in centrosymmetric materials

The bulk photovoltaic (BPV) effect of conventional ferroelectric (FE) materials has sparked a great deal of interest due to anomalous above-bandgap photovoltage. However, large bandgaps and weak photocurrents remain longstanding challenges for FE PV materials in practical applications. To address these issues, we propose a new defect-engineering strategy and demonstrate it on a narrow bandgap centrosymmetric material, BiNbO4 (BNO): the BPV effect is introduced into BNO by tuning the defect amounts, then a defect-modified homojunction structure is constructed to enhance the BPV effect. This defect engineering strategy enables synergetic effects, e.g., enhanced light absorption, FE-like depolarization field and interfacial polarization. This homojunction structure results in two-fold promotion of photovoltage and ten-fold promotion of photocurrent, compared to the defect-modified BNO sample. We believe this new strategy will break through limitations in traditional material design and pave a novel route to future multifunctional materials, especially high performance BPV materials.

Automated summary

The study introduces a new defect-engineering strategy to enhance the bulk photovoltaic effect in the ferroelectric material BiNbO4. By tuning the defect amounts and constructing a defect-modified homojunction structure, the photovoltage and photocurrent of the material were significantly improved, breaking through traditional material design limitations and paving the way for high performance BPV materials in the future.