Topic: Stability of Organic Solar Cells: From Light Harvesting, Organic/Metal Interfacial Exciton Dissociation and Charge Collection Perspectives
Speaker: Prof. Furong Zhu, Hong Kong Baptist University
Time: 10:00, December 19, 2017
Venue: Room 502, Building of State Key Laboratory of Luminescent Materials and Devices, Wushan Campus
Abstract:A comprehensive study of the stability of organic solar cells (OSCs) was conducted using a combination of optical admittance, transient photocurrent analyses and photo-induced charge extraction by linearly increasing voltage measurements. The results revealed that the imbalanced charge mobility in the donor/acceptor blend layer is one of the degradation mechanisms. Two distinguishable degradation pathways in the OSCs were identified. One was related to the localized failure in the active area, caused by the moisture encroachment. The other was associated with the oxidation process that occurred at the organic/electrode interface. Further, the presence of the unfavorable interfacial exciton dissociation at the organic/electrode interfaces compensated for the drifted photo-generated charges in the cells, leading to deterioration in the charge collection. We found that the removal of such undesired charge compensation significantly enhances the charge extraction probability and performance reproducibility, thereby improving the stability of the OSCs.