Pressure-resilient bulk photovoltaic effect in c-BeB₂

The exploration of photoelectric materials featuring superior pressure resilience holds profound implications for applications in deep-earth exploration and deep-sea imaging. Here, we predict that non-centrosymmetric c-BeB₂ maintains a robust bulk photovoltaic effect from ambient pressure up to 80 GPa, making it a promising candidate for photoelectric devices in extreme pressure conditions. The shift current σ _{y z} ^x of c-BeB₂ exhibits a broad peak predominantly distributed within the visible light region. With increasing pressure, the peak magnitude rises from 12.2 µA/V² at 2.01 eV under ambient pressure to 15.3 µA/V² at 2.27 eV at 80 GPa, representing an enhancement of nearly 25%. In contrast, the variation in the photon-energy integrated shift current across the visible spectrum remains below 10%, indicating remarkable resistance to pressure. This stability is intrinsically linked to the large bulk modulus (202 GPa) of c-BeB₂. Furthermore, pressure-induced charge inversion leads to a slight, monotonic increase in the bandgap of c-BeB₂, thereby preserving its semiconducting character. These findings provide insights for the design of photoelectric devices intended for extreme pressure environments.