Large Surface Photovoltage of WS₂/MoS₂ and MoS₂/WS₂ Vertical Hetero-bilayers

Hetero-bilayers, composed of transition metal dichalcogenide (TMD) monolayers MoS2 (1L-MoS2) and 1L-WS2, are grown on Al2O3 substrates through sulfurization pre-deposited thin films. A very smooth surface morphology the uniform contact potential difference (CPD) maps show that high-quality homogeneous TMD layers obtained. The light-induced CPD change, is, photovoltage (SPV), samples is investigated. record high SPV measured under 532 nm illumination with a power density 13 mW/cm2 from hetero-bilayers, values 800 mV for 1L-WS2/1L-MoS2 ?790 1L-MoS2/1L-WS2. Band diagrams proposed to explain observed characteristics. dependence demonstrates represent expected open-circuit voltage hetero-bilayers. obtained results suggest optimal growth proper formation vertical hetero-bilayers will enable high-efficiency ultrathin photovoltaic devices.