A first-principles study of photovoltaic, photocatalytic, and photodetection properties in a novel two-dimensional MoISb monolayer

Abstract The advent of two-dimensional (2D) materials has transformed renewable energy and optoelectronics, but current systems frequently struggle to simultaneously achieve high carrier mobility, tunable bandgaps, and structural stability. Here, we demonstrate through extensive first-principles calculations that the novel MoISb monolayer, which has a unique trigonal prismatic coordination geometry with alternating Mo-Sb and Mo-I bonds, overcomes these challenges by exhibiting: (1) remarkable thermal resilience and mechanical stability (Young’s modulus 73.476–73.725 N m −1 ), confirmed by phonon dispersion and AIMD simulations; (2) an ideal indirect bandgap of 1.38 eV with strain-tunable range (1.25–1.40 eV) for visible-light harvesting; (3) ultrahigh anisotropic electron mobility (479.31 cm 2 V −1 ·s −1 along y-direction) that surpasses conventional 2D semiconductors; and (4) pronounced polarization-dependent optical absorption (>37% at 3.5 eV) for photodetection applications. Importantly, uniaxial deformation allows the material’s band edges to be precisely aligned with water redox potentials (CBM at −4.44 eV, VBM at −5.67 eV under 1% strain), meeting the urgent need for effective solar-driven water splitting. The stability-efficiency trade-off in photovoltaics, the selectivity-yield limitation in photocatalysis, and the speed-sensitivity compromise in photodetectors are the three main energy technology gaps that MoISb fills thanks to its synergistic qualities. It also offers essential insights into the design of sophisticated ternary 2D materials.