High-Performance, Flexible, Inkjet Printed Heterostructure Photodetector for Biosensing Applications

Age-related macular degeneration (AMD), a retinal degenerative disease that results in a continuous degeneration of photoreceptors in the retina, which eventually leads to complete blindness. One approach to combat AMD is through the use of artificially implantable photodetectors that are physically placed on the retina. Interestingly, 2D materials such as photosensitive and semiconducting molybdenum disulfide (MoS2) and electrically conducting graphene have recently received tremendous promise due to their unique photonic and optoelectronic properties and their potential in various types of micro and nano-devices. In this study, a highly biocompatible 2D graphene-MoS2 photodetectors on a flexible polyimide substrate were designed, fabricated using inkjet printing to form photosensitive pixels and tested as a function of photo intensity and strain. The inkjet printed 2D heterostructure devices were photoresponsive and the photocurrent scaled proportionally with the incident light intensity, exhibiting a photoresponsivity R ~ 0.30 A/W at room temperature. The strain-dependent measurements of photocurrent with bending showed a photocurrent of Iph ~ 1.16 μA with strain levels for curvature up to ~ 0.262 cm-1. Inkjet printed graphene and MoS2 inks were also characterized using techniques such as Raman Spectroscopy, Photoluminescence (PL) and Scanning Electron Microscopy (SEM).