Spectroscopic Determination of Charge Formation Efficiency of Organic Photovoltaic Cells

The internal quantum efficiency (ΦIQ) of an organic photovoltaic (OPV) cell is governed by plural processes, i.e., the carrier formation process at the D/A interface and the carrier transfer process toward the collector electrode. Then, ΦIQ can be decomposed into the carrier formation (ΦCF) and carrier transfer efficiencies (ΦCT). By combination of femtosecond time-resolved and electrochemical spectroscopies, we determined absolute values of ΦCF of F8T2/PC71BM, P3HT/PCBM, and PTB7/PC71BM solar cells. We found that ΦCF at 400 nm of the F8T2/PC71BM cell is higher than those of the P3HT/PCBM, and PTB7/PC71BM cells, although ΦIQ at 400 nm is the lowest. Copyright © Taylor & Francis Group, LLC.