Thiophene is widely used in organic photovoltaics due to its excellent charge transport properties, simple synthesis, and high stability. In this paper, two simple oligothiophenes, namely,DC5Tand2FDC5Twith rhodanine-flanked structures were synthesized and used as donors in nonfullerene small-molecule organic solar cells (NSM-OSCs). Compared toDC5T,2FDC5Twith fluorine atoms substituted on the conjugated backbone exhibited a downshifted highest occupied molecular orbital (HOMO) energy level and blue-shifted light absorption. WithIDIC-4Fas a small-molecule acceptor, the2FDC5T-based device exhibited much higher short-circuit current density and open-circuit voltage than theDC5T-based device. As a result, a promising power conversion efficiency (PCE) of 9.02% was achieved for the2FDC5T/IDIC-4Fdevice, which was 28% higher than that of theDC5T/IDIC-4Fdevice (PCE = 7.03%). Further research indicated that fluorination on the oligothiophene donor assisted the optimization of the active layer morphology and the reduction in the trap-assisted recombination in the device, which could deeply explain the improvement in efficiency.
ASJC Scopus subject areas
- Renewable Energy, Sustainability and the Environment
- Fuel Technology
- Energy Engineering and Power Technology