Conformal Integration of an Inkjet-Printed PbS QDs-Graphene IR Photodetector on a Polymer Optical Fiber

Hybrid graphene-colloidal PbS quantum dots (QDs) phototransistors are promising to overcome the geometrical restrictions of photodetectors to flat substrates. While compatible with conformal manufacturing, the experimental demonstration of their application to curved surfaces remains elusive. This work demonstrates the seamless integration of an infrared (IR) photodetector to a polymer optical fiber (POF) by wrapping graphene around the POF of 1 mm in diameter and, subsequently, inkjet printing of PbS QDs onto the curved surface. The device acts as a functional coating and detects infrared light propagating through the POF without interrupting the waveguide. The formulated alpha-terpineol and hexane co-solvent ink supports drop-on-demand placement with a resolution of 50 mu m and is colloidally stable over 7 months. A responsivity map over gate voltage and temperature (300 to 80 K) of a device, fabricated on a common flat substrate, reveals a responsivity of R approximate to 1 x 10(3)AW(-1) (irradiance approximate to 1 mu W cm(-2)) and a detectivity of D* approximate to 1 x 10(10) Jones at 1.6 mu m wavelength. This work brings the integration of this cost-effective and adaptable hybrid detector approach closer to multifunctional e-textiles and will, notably, help to improve the interfacing of the skin as desired for wearable and non-invasive healthcare applications.