Pressure-induced superconductivity and enhanced optoelectronic property in the ternary pentagonal semiconductor PdPSe

The ternary van der Waals (vdW) pentagonal semiconductor PdPSe has gathered significant attention due to its unique anisotropic structure and exotic optoelectronic properties originating from the distinct Cairo pentagonal tiling topology. Here, we report pressure tuning of the photoelectronic and electronic properties of pentagonal PdPSe. We show that the photocurrent is enhanced by over two orders of magnitude at 25.9 GPa and suddenly disappears upon further compression. Meanwhile, metallization and superconductivity simultaneously occur at around 25 GPa. The superconducting critical temperature ${T}_{\mathrm{c}}$ initially increases and then becomes robust up to \ensuremath{\sim}60 GPa. Synchrotron x-ray diffraction and Raman experiments consistently indicate the disappearance of photocurrent and the occurrence of superconductivity are both correlated to the formation of a high-pressure amorphous phase. As a result of the irreversible nature of the amorphization, metallic conductivity retains near ambient pressure in depressurized PdPSe. The synchronous evolution of structural, photoelectronic, and electronic properties elucidates a deep understanding of the structure-property relationship and emergent functionalities in a vdW pentagonal semiconductor via pressure modulation. This finding further provides an opportunity for tuning, understanding, and exploring the related vdW pentagonal materials under extreme conditions.