Effects of electric fields on the conduction of polyvinyl alcohol (PVA)/ZnO films by photoluminescence analysis

We verified the electrical properties of zinc oxide (ZnO) and hydrated polyvinyl alcohol (PVA)/ZnO films under the influence of electric field through photoluminescence (PL) analysis. The ZnO films were deposited by sputtering on A-N-B substrates that had nonconductive areas (N) between A and B electrodes. The PVA/ZnO films were prepared by spin-coating PVA gel on top of the ZnO film. Current–voltage (I–V) data analysis showed that the conductivity values of the ZnO films significantly increased in the presence of PVA gel. Large amounts of free electrons and oxygen vacancies (V_o) were generated by the chemisorption reaction of PVA gel with ZnO and detected by PL spectra produced without the presence of an electric field (0 V). The Fermi-energy level for a PVA/ZnO film approaches the conduction band of ZnO because of many free electrons in the film. The variations of both the free electron and V_o densities for ZnO and PVA/ZnO films were analyzed using PL spectra in the presence of various electric fields (>0 V). The conduction mechanism of PVA/ZnO was explained and related to the variations of both the free electron and V_o densities as revealed by the PL spectral analysis.