Physical Properties and Photovoltaic Application of Semiconducting Pd(2)Se(3) Monolayer

Palladium selenides have attracted considerable attention because of their intriguing properties and wide applications. Motivated by the successful synthesis of Pd(2)Se(3) monolayer (Lin et al., Phys. Rev. Lett., 2017, 119, 016101), here we systematically study its physical properties and device applications using state-of-the-art first principles calculations. We demonstrate that the Pd(2)Se(3) monolayer has a desirable quasi-direct band gap (1.39 eV) for light absorption, a high electron mobility (140.4 cm(2)V(−1)s(−1)) and strong optical absorption (~10(5) cm(−1)) in the visible solar spectrum, showing a great potential for absorber material in ultrathin photovoltaic devices. Furthermore, its bandgap can be tuned by applying biaxial strain, changing from indirect to direct. Equally important, replacing Se with S results in a stable Pd(2)S(3) monolayer that can form a type-II heterostructure with the Pd(2)Se(3) monolayer by vertically stacking them together. The power conversion efficiency (PCE) of the heterostructure-based solar cell reaches 20%, higher than that of MoS(2)/MoSe(2) solar cell. Our study would motivate experimental efforts in achieving Pd(2)Se(3) monolayer-based heterostructures for new efficient photovoltaic devices.