Growth of Well-Aligned ZnO Nanorod Arrays and Their Application for Photovoltaic Devices

We have fabricated well-aligned ZnO nanorod arrays (ZNRAs) on indium tin oxide-coated glass substrates by a facile chemical bath deposition method. We used field-emission scanning electron microscope, x-ray diffraction and UV–Vis absorption spectroscopy to study the morphology, crystalline structure and optical absorption of the fabricated ZNRAs, respectively. The results showed that ZnO nanorods stood almost perpendicularly on the substrate, were about 30–50 nm in diameter and 800–900 nm in length, and were wurtzite-structured (hexagonal) ZnO. In addition, well-aligned ZNRAs exhibited a weak absorption in the visible region and had an optical band gap value of 3.28 eV. Furthermore, a hybrid ZNRAs/polymer photovoltaic device was made, under 1 sun AM 1.5 illumination (light intensity, ∼100 mW/cm2), and the device showed an open circuit voltage (Voc) of 0.32 V, a short circuit current density (Jsc) of 7.67 mA/cm2, and a fill factor (FF) of 0.37, yielding an overall power conversion efficiency of 0.91%. Also, the exciton dissociation and transportation processes of charge carriers in the device under illumination were explained according to its current density–voltage (J–V) curve and the energy level diagram.