Porphyrin small molecules containing furan- and selenophene-substituted diketopyrrolopyrrole for bulk heterojunction organic solar cells

• Porphyrin small molecules containing furan and selenophene are synthesized.
• Chalcogen atoms could change the absorption and tune the energy levels regularly.
• The OSCs based on the two molecules show PCEs of 4.26% and 5.81%, respectively.

Two porphyrin small molecules substituted with either furan- or selenophene-linked diketopyrrolopyrrole units are designed and synthesized. The impacts of the O and Se chalcogen atoms in the linking 5-membered ring in these new donor materials on the performance of organic solar cells are discussed and contrasted with the previously described thiophene analogue. The heavy atoms broaden the absorption and narrow the bandgap by tuning the energy levels regularly. Furthermore, the selenophene containing analogue shows better miscibility and smaller phase separation with [6,6]-phenyl C61-butyric acid methyl ester (PC61BM) than the furan analogue. The optimized organic solar cells based on the furan and the selenophene containing species are achieved in the presence of pyridine and 1,8-diiodooctane additives with power conversion efficiencies of 4.3% and 5.8%, respectively, under simulated AM 1.5 illumination (100 mW cm−2).

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