Design and Performance Study of High-Efficiency Self-Powered Photodetectors Based on ZnO/X₂CO₂ (X=Zr, Hf) Heterojunctions

This study delves into the structural characteristics, electronic properties, and application potential of ZnO/Zr2CO2 and ZnO/Hf2CO2 heterojunctions for photodetectors. Through lattice matching and formation energy calculations, the stable structures of the two heterojunctions were determined. The band structures were further calculated under PBE and HSE06 functionals. Subsequently, mechanical properties, −COHP, ELF, electrostatic potential, and average charge density were analyzed. The calculations of carrier mobility showed that the electron mobility of ZnO/Hf2CO2 is 25654 cm2/Vs in the zigzag direction and 8269 cm2/Vs in the armchair direction. The electron mobility of ZnO/Hf2CO2 is much higher than that of ZnO/Zr2CO2, and electrons have a greater migration advantage in the zigzag direction. The two heterojunctions were constructed as self-powered photodetectors, and the photocurrent, Seebeck coefficient, and transmission coefficient were calculated. The photocurrent peak value of ZnO/Zr₂CO₂ heterojunction is 1.38 a₀²/photon, and the Seebeck coefficient is 1.50 mV/K. The analysis indicated that ZnO/Hf2CO2 has more stable thermoelectric conversion efficiency over a wide temperature range, while the performance of ZnO/Zr2CO2 can be optimized by adjusting the temperature. These research findings provide important theoretical basis for designing efficient photovoltaic conversion devices.