Fullerene derivatives are used as electron acceptors in organic solar cells. CH2 addends can effectively raise fullerene lowest unoccupied molecular orbital (LUMO) energy levels, which leads to high open-circuit voltage (Voc). As the smallest addend, CH2 does not affect fullerene packing in the solid state, thus keeping good electron mobility for the acceptors.
Stepwise replacement of o-quinodimethane addends with CH2 addends in 54π fullerenes improves the electron mobility of fullerene, enhances crystallinity of poly(3-hexylthiophene) (P3HT), increases donor-acceptor interfaces, and reduces bimolecular recombination, thus enhancing the power conversion efficiency of fullerene:P3HT solar cells remarkably from 2.26 % to 6.25 %. This is reported by the team of Liming Ding from the National Center for Nanoscience and Technology, Beijing, China.
This work clearly demonstrates the function of CH2 addends in fullerenes, which is enlightening for designing high-performance fullerene acceptors for organic solar cells.
- Function of CH2 Addends on 54π Fullerene Acceptors
Shan Chen, Zuo Xiao, Dan He, Lina Ma, Liming Ding
Asian J. Org. Chem. 2014.