Electrical characteristics of ternary solar cells based on PTB7:PCBM:ICBA

摘要

Ternary bulk heterojunction solar cells based on the electron donor PTB7-Th and the electron acceptors PC71 BM and ICBA are fabricated with an optimum concentration of ICBA of 15 wt% and characterized electrically. Current density-voltage (J-V) and impedance spectroscopy characteristics are discussed. Characteristics under dark conditions are modeled to find a well predictable value of the open circuit voltage (VOC) which is compared with the experimental value. From impedance spectroscopy, specifically from capacitance-voltage characteristics, a relaxation or recombination time between 10^-3 and 10^-5s for charge carriers is observed. Our results show that this analysis allows to verify whether recombination determining VOC also determines recombination under dark conditions for ternary solar cells.