Theoretical Prediction of 2D Y₂CTI (T = Br, Cl, F, H) Janus MXene Monolayers for Photovoltaic Applications

Two-dimensional Janus monolayers have garnered attention as promising materials for photovoltaic applications due to their distinctive structural, electronic, and optical properties. In this work, we investigate the solar harvesting efficiency of Janus Y₂CTI (T = Br, Cl, F, H) MXene monolayers using density functional theory and a maximally localized Wannier function tight-binding framework. Our results demonstrate an outstanding power conversion efficiency ranging from 31 to 32% for the investigated materials. These values were calculated at 300 K, incorporating the quasi-particle effects and considering the constraints imposed by the Shockley-Queisser limit. Furthermore, excitonic effects induced by quantum confinement contribute to exciton binding energies between 228 and 325 meV and indirect band gaps ranging from 1.23 to 1.33 eV, depending on compounds. Our results indicate a high potential of Janus Y₂CTI MXene monolayers for photovoltaic applications and provide insights into their excitonic contribution.