2018 Volume 138 Issue 11 Pages 1298-1304
The conjugated system of polymer has an important role on the photovoltaic properties of a polymer bulk heterojunction (BHJ) solar cell. In this work, we focused on the impact of π-conjugation length of poly(3-hexylthiophene) (P3HT) on the power conversion efficiency of P3HT:phenyl-C61-butyric-acid methyl ester (PCBM) BHJ solar cell. The π-conjugation length of P3HT is systematically controlled through partial bromination at the 4-position of thiophene ring, which elucidated the correlation between the degree of P3HT bromination and the photovoltaic properties of Br-P3HT:PCBM BHJ solar cells. The energy conversion efficiency of the unbrominated (pristine) P3HT:PCBM solar cell is 2.3%, whereas that of Br-P3HT:PCBM solar cell with approximately 7% bromination falls to 1.4%. The present results suggest that the π-conjugation length of about 14 thiophene rings is insufficient for achieving efficient charge transport.
The transactions of the Institute of Electrical Engineers of Japan.C
The Journal of the Institute of Electrical Engineers of Japan