| AVS 62nd International Symposium & Exhibition | |
| Energy Frontiers Focus Topic | Monday Sessions |
| Session EN+AS+EM+NS+SE+SS+TF-MoA |
| Session: | Solar Cells II |
| 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 D.S. Ginger, University of Washington |
| Correspondent: | Click to Email |
The better understanding of the underlying mechanisms is essential for the further development of highly efficient organic photovoltaics (OPVs) devices. In this paper, the transient photovoltage (TPV) and charge extraction (CE) measurements in combination with the synchrotron radiation photoemission spectroscopy (SRPES) were used to gain insights intothe correlation between the microscopic interfacial properties and macroscopic device performance. The OPV devices based on PCDTBT: PC70BM with Ca interlayer were studied as a reference system to investigate the interfacial effects on device performance. The charge carrier decay dynamics demonstrated that the device with the Ca interlayer exhibited a lower recombination constant (krec) than that only with the Al cathode at a given charge carrier density (n). In addition, the interfacial energy band structures indicated that the strong dipole moment produced by the Ca interlayer can facilitate electron extraction as well as drive hole away at the cathode/polymer interface, resulting in retarding interfacial recombination losses. Finally, we examined the device performance with the Ca interlayer to find that the efficiency is improved by 28% as compared to that without the Ca interlayer, which shows good correlation with the observed interfacial properties.