AVS 61st International Symposium & Exhibition
    Energy Frontiers Focus Topic Wednesday Sessions
       Session EN+AS+EM-WeA

Paper EN+AS+EM-WeA12
Study on the Correlation between Electrode-Active Layer Interfaces and Performance of Polymer Solar Cells

Wednesday, November 12, 2014, 6:00 pm, Room 315

Session: Organic-Inorganic Interfaces for Energy
Presenter: Huanxin Ju, University of Science and Technology of China
Authors: H.X. Ju, University of Science and Technology of China
J.F. Zhu, University of Science and Technology of China
Correspondent: Click to Email
The PSCs were fabricated with different cathodes (Ca/Al and Al) as the electron-collection layers and with PCDTBT (poly[N-9”-hepta-decanyl-2,7-carbazole-alt-5,5-(4’,7’-di-2-thienyl-2’,1’,3’-benzothiadiazole)]) and PC70BM ([6,6]-phenyl-C71-butyric acid methyl ester) as the active layers. The Ca/Al interlayer significantly improves the open circuit voltage (VOC), short circuit current (JSC), fill factor (FF) so as to improve the PCE in comparison with Al as the cathode. In order to understand how the electrodes affect the device performance, the Ca/PCDTBT and Al/PCDTBT interfaces were investigated by transient photovoltage (TPV), charge extraction (CE) and synchrotron radiation photoemission spectroscopy (SRPES). The TPV and CE measurements were used to determine the charge carrier lifetime and density. Charge carrier recombination rate constant was found to be much smaller in the device with Ca/Al cathode as compared to that with Al cathode. Energy band diagrams and interfacial chemical reactions were characterized using high-resolution SRPES. The results indicate that the Ca interlayer can induce the stronger dipole moment, which facilitates electrons collection and drives holes away at the cathode/polymer interface. The device performance was improved because of the lower recombination.