Donor–acceptor interface modification by zwitterionic conjugated polyelectrolytes in polymer photovoltaics

• DOI: 10.1039/c3ee00060e
• Publication Date: 2013-03-19T12:09:28Z
• Authors: Abhishek Kumar; Giuseppina Pace; Artem A. Bakulin; Junfeng Fang; Peter K. H. Ho; Wilhelm T. S. Huck; Richard H. Friend; Neil C. Greenham
• Keywords: 540; 7. Clean energy; Physical Organic Chemistry

We report that we can enhance the performance of polymer photovoltaics by introducing materials with dipoles at the donor–acceptor interface of the polymer solar cells. We use a zwitterionic conjugated polyelectrolyte (ZCPE) as an interfacial layer in a model bi-layer system consisting of donor and acceptor polymers. We find an increase in short-circuit current and fill factor when a 2 nm thin layer of ZCPE is introduced between donor and acceptor polymers. Absorption of light in the ZCPE interlayer contributes to the photocurrent, and, as revealed by time-resolved pump–push optical spectroscopy, the interlayer reduces the probability of electron–hole recombination at the donor–acceptor interface.