Flexible electronics and optoelectronics based on monolayered, semiconducting transition metal dichalcogenides (TMDCs) channel have recently received attention as the 2D structure possess superior mechanical, optical, and electrical properties. However, there is a lack of understanding of strain-dependent electrical and photoelectrical properties in the electrode-TMDC channel system. Here, two-terminal flexible device is fabricated and strain-engineered contact barrier modulation between monolayer MoS 2 channel and Au electrode is shown. It is found experimentally through in situ strain electrical and kelvin probe force microscope measurements that tensile strain lowers the contact energy barriers between MoS 2 and Au, in which the changes in the contact barriers is attributed to the strain-induced increase of the electron affinity in MoS 2 monolayer. Furthermore, the strain-induced barrier modulation is also shown to affect photoresponse behaviors in a MoS 2 flexible photodetectors through bending of energy bands that affect photogenerated carrier transport and electron-hole recombination. These findings present important pathway toward designing flexible devices based on 2D TMDCs.

Chemical vapor deposition (CVD) synthesis for two-dimensional (2D) transition-metal dichalcogenides (TMDCs) is fundamentally important for realizing high-quality single crystals of TMDCs for future electronic and optoelectronic device applications. However, CVD synthesis of TMDCs generally requires a high synthetic temperature (>700 °C), which limits the choice of growth substrates and their broad applications. In this work, we present direct CVD synthesis of 2D MoS 2 on glass. The CVD growth temperature was significantly decreased to 500 °C by employing carbothermal reduction, which uses carbon as the catalyst for reducing the thermal decomposition temperature of MoO 3 precursors. MoS 2 single crystals grown on glass showed no observable degradation in electrical, optical, and structural properties compared to MoS 2 grown at high temperatures. The MoS 2 grown on glass exhibited field effect mobility around 7.6 cm 2 V −1 s −1 and a high ON/OFF ratio of up to 10 7 , photoresponsivity up to 40 A/W, and stable and repeatable photocurrent. These findings demonstrate a promising strategy in the CVD growth of 2D materials and the design of their flexible and transparent devices.