Room-Temperature High-Performance Photodetector and Phototransistor Based on PdSe₂/ZnIn₂S₄ Alloy Heterojunctions

Various semiconductor devices have been developed based on 2D heterojunction materials owing to their distinctive optoelectronic properties. However, to achieve efficient charge transfer at their interface remains a major challenge. Herein, an alloy heterojunction concept is proposed. The sulfur vacancies in ZnIn₂S₄ are filled with selenium atoms of PdSe₂. This chemically bonded heterojunction can significantly enhance the separation of photocarriers, providing notable advantages in the field of photoelectric conversion. As a demonstration, a two-terminal photodetector based on the PdSe₂/ZnIn₂S₄ heterojunction materials is fabricated. The photodetector exhibits stable operation in ambient conditions, showcasing superior performance in terms of large photocurrent, high responsivity (48.8 mA W^-1) and detectivity (1.98 × 10¹¹ Jones). To further validate the excellent optoelectronic performance of the heterojunction, a tri-terminal phototransistor is also fabricated. Benefiting from gate voltage modulation, the photocurrent is amplified to milliampere level, and the responsivity is increased to 229.14 mA W^-1. These findings collectively demonstrate the significant potential of the chemically bonded PdSe₂/ZnIn₂S₄ alloy heterojunction for future optoelectronic applications.