Direct Roll Printed Si and GaAs based Flexible Photosensors

The integration of high mobility inorganic materials such as silicon (Si) and gallium arsenide (GaAs) onto flexible substrates is a challenging yet crucial step for the development of high-performance flexible electronics. The development of such integration technologies could also lead to hybrid and heterogeneous integration. Herein, we present 'direct roll transfer printing (DRTP)' - the roll-based manufacturing platform – that allows integration of nano to micro scale structures of inorganic semiconductors onto wide variety of substrates and their subsequent processing leading to different type of devices. The DRTP is used here to develop Si and GaAs nano/microstructures based flexible photosensors. The extensive characterisation of these photosensors shows excellent response of Si nanomembranes (NMs) based device in visible-ultraviolet (UV)-near infrared (NIR) light illumination. The high-speed response (rise time τ Rise = 205μs and fall time τ Fall = 200 μs), and a peak responsivity of 2.48 A/W to UV light at zero bias voltage show the exceptional self-powered operation of these sensors. The printed GaAs based photosensors operate at low voltage (1V) and show high-speed response (rise time (2.5 ms) and recovery time (8 ms)), and high responsivity (>10 4 AW –1 ) under UV-NIR light illumination. These results demonstrate the versatility of DRTP approach towards printing of different types of inorganic semiconductors for hybrid and heterogeneous integration of high-performance flexible electronics.