Low cost flexible 1.1 μm -1.6 μm photodetector fabricated by hydrothermal grown large area MoSe2 nanostructures

Infrared photoresponse in large area MoSe₂ nanostructured films on flexible substrates has been presented in this work. Nanostructures of MoSe₂ have been grown by hydrothermal route using sodium molybdate and selenium (Se) as a precursor in hydrazine and water solution. The process parameters such as ambient pressures and temperature have been optimized to get the nanostructure with superior photosensitivity in IR regime. The adopted synthesis process results in the suspended particles composed of MoSe₂ nanostructure, which later transfer in ethanol. This solution has been coated on flexible poly-ethylene terephthalate (PET) substrates for the device fabrication by dip coating. Scanning electron microscopy and high-resolution transmission electron microscopy (HR-TEM) reveals that the as-prepared MoSe₂ has particle-like features. The photoresponse of the devices was measured in the wavelength range 1000 nm -1600 nm. As-obtained flexible photodetectors showed responsivity of ~ 2.6 A/W (at 500 mV bias) and rise/fall time 3.9 sec and 2.9 sec under the illumination of 1550 nm. It was also noted that for the small bias voltages, our MoSe₂ films possess excellent photoresponse as the at 50 mV bias the responsivity was recorded up to 127 mA/W for 1550 nm light). The simple approach used in this work should facilitate the development of low cost and low power IR photodetectors for next-generation flexible optoelectronics.