Preparation and characterization of nano-scale ZnO as a buffer layer for inkjet printing of silver cathode in polymer solar cells

Less-populated and well-isolated ZnO nanorods were prepared from a simple solution method by using polyethylene glycol (PEG) surfactant molecules. The structural and morphological information provided by X-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM) demonstrated the high purity of the ZnO nanorods that were free from any unknown impurities. Furthermore, annealing treatment was used to increase the length of the ZnO nanorods further at an elevated temperature. This ZnO was used as a buffer layer for polymer solar cells (PSCs) in the device configuration of ITO/ PEDOT:PSS/P3HT-PCBM/ZnO/Ag, in which the Ag cathode was prepared by the inkjet printing method using silver ink. The present study discusses and compares the performance of the devices with and without the ZnO buffer layer.