Tunable Voc in polymer/ZnO array hybrid solar cells by ZnO interlayer with different nano-topographies

In this paper, two different ZnO nano-topographies of thin film (TF) and quantum dots (QDs) were separately introduced as an interlayer at the polymer/ZnO nanorod array (NRA) heterojunction interface for hybrid solar cells (HSCs), and their performances were studied comparatively. It was found that the ZnO-TF and ZnO-QDs as interlayer got the reverse actions on tuning device V-oc. Compared with that of pristine ZnO-NRA based HSCs, the ZnO-TF layer will obviously reduce the device Voc, however, the ZnO-QDs layer can dramatically improves the device Voc. Based on calculated ZnO conduction band edge shift, photoluminescence, and intensity modulated photovoltage spectra measurements, it was found that the changes of Voc originated from the tunable interfacial defects concentration by interlayer. The interfacial defects concentration could affect the interfacial dipole numbers, which would shift conduction band edge in the ZnO nanorod and thereby changing the Voc. Our results also indicated that interfacial defects seemingly could be utilized for improving HSCs performance at times.