Molecular tailoring of donor and acceptor materials of organic solar cells for improvement of their optoelectronic properties

Improvement in the efficiency of organic solar cell (OSC) is one of the hot topics of the modern-day research. Despite environment friendliness and several other practical advantages, the power conversion efficiency (PCE) of OSC has not yet achieved the levels of the commercial inorganic solar cells. In this context, molecular tailoring of the donor and acceptor materials can help in alignment of the energy levels in order to improve PCE. In this study, we demonstrate the introduction of different functional groups on the most widely used donor and acceptor materials namely poly(3-hexylthiophene) (P3HT) and fullerene, respectively. P3HT was successfully converted into poly(4-bromo-3-hexylthiophene), poly(4-chloro-3-hexylthiophene), and poly(3-hexyl-4-nitrothiophene) through bromination, chlorination, and nitration reactions, respectively. Similarly, fullerene was converted into phenyl-C61-pentanoic acid methyl ester, phenyl-C61-pentanoic acid, and methyl-2-C61 propionate. The success of different modifications on P3HT and fullerene was monitored by 1H NMR spectroscopy. Finally, the optoelectronic properties after the above-mentioned modifications were evaluated by UV–Vis spectroscopy and cyclic voltammetry.