Pressure optimized 2D-IV monochalcogenide for enhanced photovoltaic performance in skyscraper-integrated solar cell: A computational insight

Abstract

Two-dimensional (2D) group IV-monochalcogenides, particularly germanium sulfide (GeS), germanium selenide (GeSe), and germanium telluride (GeTe) exhibit remarkable potential for skyscraper-integrated solar cell (SISC) applications due to their tunable electronic and optical properties under high pressure. This study investigates the structural, electronic, and optical responses of these materials under increasing pressure for photovoltaic applications using density functional theory (DFT) with the GGA-PBE exchange-correlation functional and the HSE06 hybrid functional. Phonon calculations confirm thermodynamic stability, with no negative frequencies observed. A nonlinear variation has been observed in structural parameters under increasing pressure, leading to significant changes in optical and electronic properties. Specifically, the band gap of 2D-GeSe monolayer alternation undergoes three different responses under pressure. It initially decreases for external pressure below 5 GPa, remains stable between 5 and 25 GPa, and increases steadily between 30 and 50 GPa. The highest value of absorption coefficient (α) (1.234 × 10⁵ cm⁻¹) is observed at 5 GPa due to the shifting of the indirect band gap (1.738 eV) to the direct band gap (1.851 eV) of 2D-GeS. Besides this, the 2D-GeS shows a remarkable performance in terms of open circuit voltage (0.680 V) and maximum power output (0.52 × 10⁻² W) at 5 GPa, suggesting its integration potential in multi-junction solar cells in skyscraper. 2D-GeS based solar cell not only generate energy but also contribute to insulation and building energy efficiency, offering a cost-effective and visually appealing solution for sustainable urban design.