Novel Self-Powered Photodetector with Binary Photoswitching Based on SnSx/TiO2 Heterojunctions

Binary photoresponse characteristics can help realize optical signal processing and logic operations. UV photodetectors (PDs) with SnS x nanoflakes and TiO 2 nanorod arrays (NRs) show a novel binary photoswitching behavior (change in current from positive to negative) by manipulating the light wavelength without an external power source, utilizing the interfacial recombination of the photogenerated carriers in the type-I SnS x /TiO 2 heterojunctions. The enhanced responsivity ( R* ), detectivity ( D * ), and fast photoresponse time for self-powered SnS x /TiO 2 PDs can be achieved by adjusting the phase ratio of SnS and SnS 2 nanoflakes. The binary photoswitching in the self-powered UV PDs can be applied in the encrypted optical signal processing and imaging in some special conditions without external bias.