A photodiode with high rectification ratio and low turn-on voltage based on ZnO nanoparticles and SubPc planar heterojunction

A simple photodiode based on boron subphthalocyanine chloride (SubPc) organic semiconductor and zinc oxide (ZnO) inorganic nanoparticle (NP) thin films planar heterojunction was fabricated. The current density–voltage (J–V) characteristics of ITO/ZnO NPs/SubPc/Ag device in dark and under 20 mW/cm2 illumination power with a solar simulator were investigated in detail. Measurement results showed that the device exhibited good rectifying behaviors in dark and under illumination. A high rectification ratio (RR) of 607 at ±1.65 V and a low turn-on voltage of 0.9 V were achieved for the device in dark, such high RR was ascribed to high electron mobility of ZnO NPs and large ZnO NPs/SubPc interface in the device. Also, the photoresponsive mechanism of the photodiode was illuminated in term of the schematic band diagram and the transportation process of charge carriers in the device.