Photo-induced characteristic study of the smallest fullerene fragment, 1,6,7,10-tetramethylfluoranthene as an acceptor

In the present study, a novel solution-processable 1,6,7,10-tetramethylfluoranthene (1), as the smallest fragment of fullerene, is synthesized and systematically studied for use as a non-fullerene acceptor in an organic solar cell (OSC). Molecule 1 has the potential to be synthesized on a large scale. Optical and electrochemical studies revealed that 1 has a high absorption range and an appropriate band gap, which is compatible with poly(3-hexylthiophene-2,5-diyl) (P3HT) as a donor. The morphology showed high intermixed blend with uniform distribution of donor-acceptor molecules. Steady state and time resolved photoluminescence studies showed efficient charge separation from the donor and acceptor. These studies can be confirmed by the conventional OSC device structure employing a blend of P3HT:1, which gives a power conversion efficiency (PCE) of up to 0.71% with an open circuit voltage (V-OC) of 0.52 V and a fill factor (FF) of 44.89%. Despite this, the significant stability of the device, even after 60 h in open air, demonstrates that this molecule shows promising output and the result can be enhanced in the future with further optimization.