Panchromatic Ternary Organic Solar Cells with Porphyrin Dimers and Absorption-Complementary Benzodithiophene-based Small Molecules

Diketopyrrolopyrrole–ethynylene-bridged porphyrin dimers are capped with electron-deficient 3-ethylrhodanine (A2) via a π-bridge of phenylene ethynylene, affording two new acceptor–donor–acceptor structural porphyrin dimers (DPP-2TTP and DPP-2TP) with strong absorption in ranges of 400–550 nm (Soret bands) and 700–900 nm (Q bands). Their intrinsic absorption deficiency between the Soret and Q bands could be perfectly compensated by a wide-bandgap small molecule DR3TBDTTF (D*) with absorption at 500–700 nm. Impressively, the optimal ternary device based on the blend films of DPP-2TPP, DR3TBDTTF (20 wt %), and PC71BM shows a PCE of 11.15%, whereas the binary devices based on DPP-2TTP/PC71BM and DPP-2TP/PC71BM blend films exhibit PCEs of 9.30 and 8.23%, respectively. The high compatibility of the low bandgap porphyrin dimers with the wide-bandgap small molecule provides a new threesome with PC71BM for highly efficient panchromatic ternary organic solar cells.