Pacific Rim Symposium on Surfaces, Coatings and Interfaces (PacSurf 2018)
    Energy Harvesting & Storage Tuesday Sessions
       Session EH-TuP

Paper EH-TuP4
Study of Charge Transfer across C60/BCP and BCP/Ag Interfaces Using Core-Hole Clock Spectroscopy

Tuesday, December 4, 2018, 4:00 pm, Room Naupaka Salon 1-3

Session: Energy Harvesting and Storage Poster Session
Presenter: Tetsuya Miyazawa, SOKENDAI, Japan
Authors: T. Miyazawa, SOKENDAI, Japan
K. Ozawa, Tokyo Institute of Technology, Japan
K. Kanai, Tokyo University of Science, Japan
T. Sakurai, Tsukuba University, Japan
K. Mase, KEK, Japan
Correspondent: Click to Email
Electronic properties at organic/metal and organic/organic interfaces affect the efficiencies of organic electronic devices such as organic solar cells, perovskite solar cells, and organic field effect transistors. Peuman et al. have found that the conversion efficiency of the organic solar cell is improved when bathocuproine (BCP) is inserted as buffer layer between the organic molecule of acceptor and negative electrode [P. Peuman et al., Appl. Phys. Lett. 76, 2650 (2000).]. In order to reveal the role of buffer layers, we investigated C60/BCP and BCP/Ag layered systems by resonant photoelectron spectroscopy and X-ray absorption spectroscopy. A core-hole clock analysis was carried out to examine transfer times of an electron from C60 to BCP and that from BCP to Ag. The sample was prepared by the procedure that monolayer of BCP was deposited on Ag thin film and then monolayer of C60 was deposited on the BCP. The charge transfer times from LUMO+1 of BCP to Ag and C60 to BCP were calculated to be 2.5 fs and less than 60 fs, respectively. In the photoelectric conversion of organic solar cells, electrons generated by exciton separation transfer from organic molecule of acceptor to negative electrode. These results suggest that ultrafast charge transfers across C60 to BCP and BCP to Ag are one of the role of buffer layers to improve conversion efficiency of organic solar cells.