Dual-polarity response in self-powered ZnO NWs/Sb2Se3 film heterojunction photodetector array for optical communication

Self-powered photodetectors (PD) have great potential applications in visible light communication (VLC) systems due to their unique advantages such as energy saving and low cost, where color shift keying (CSK) is widely utilized to meet the requirements of non-negative light intensity modulation. However, at least two PDs with filters are needed to decode the optical signals, greatly increasing the device cost and complicating the communication system. Here, we report a new type of dual-polarity response PD with an adjustable polarity switching wavelength, where the output signals are positive and negative in long and short wavelength regions, respectively. The dual-polarity response is a consequence of the competition between photovoltaic (PV) effect of ZnO NWs/Sb2Se3 film p-n junction and pohtothermoelectric (PTE) effect of Sb2Se3 thin film. As compared with current PDs in CSK systems, our PD can work without any filter and one PD can realize the function of two traditional PDs. This new PDs have the potential applications in optical communication systems and filterless color discrimination.