A novel planar integration of all-solid-state capacitor and photodetector by an ultra-thin transparent sulfated TiO2 film

Recently, much effort has been dedicated to achieve integrated nanodevices with energy storage capability in order to meet the demands of multifunctional electronics. Here we demonstrate the concept based on a sulfated TiO2 film that integrates a transparent all-solid-state capacitor and a self-powered photodetector simultaneously for the first time. The sulfated TiO2 film shows a high capacitance of 140 F/cm(3), and offers a bifunctionality of the active material and the electrolyte that broadens the operating voltage to 2.3 V. Especially, the film can be charged via a pulsed voltage; then it performs with high responsivity and shows very fast response to UV light without any external bias voltage. Besides, the protonation/deprotonation in the sulfated TiO2 has been also proposed to enhance the excellent charge storage and the photoresponse properties of the film. (C) 2014 Elsevier Ltd. All rights reserved.