Visible light emission and UV light detection properties of solution-grown ZnO/polymer heterojunction diodes on stainless steel foil

Heterojunction devices were prepared from ZnO films grown by successive chemical solution deposition on flexible stainless steel substrate and from p-type polymer films of PEDOT:PSS. The effect of air annealing and H2O2 treatment of ZnO on the optoelectronic properties of devices were investigated. Various techniques were utilized for the characterization of ZnO films and the evaluation of devices. Devices with diode type current-voltage and capacitance-voltage characteristics can be fabricated if the hydroxyl content of the as-grown ZnO is removed by annealing the film in air (400 °C, 20 min). H2O2 treatment of ZnO for 10 min followed by air annealing yields a high resistivity interfacial layer required for the device to exhibit visible electroluminescence. A typical light emitting diode shows a current rectification factor of ∼100 (±2 V), ideality factor of 3.0, barrier height of 1.1 eV and reverse-bias breakdown voltage of −36 V. Fabricated diodes show self-powered visible-blind UV photodetection characteristics in the wavelength range of 274-375 nm.