A Carbonylated Terthiophene-Based Twisted Polymer for Efficient Ternary Polymer Solar Cells

In polymer solar cells (PSCs), it is difficult for twisted conjugated polymers to achieve high power-conversion efficiency (PCE) as donors due to their low charge carrier mobilities and poor bulk heterojunction morphologies. In this work, a new twisted conjugated polymer (P3TCO-1) with excellent solubilities (above 30 mg mL^-1 ) in common organic solvents at room temperature is reported. UV-visible absorption spectra and cyclic voltammetry indicate that P3TCO-1 has a wide optical bandgap of 1.90 eV and deep HOMO level of -5.39 eV. In binary PSCs, P3TCO-1:ITIC-based device shows a PCE of 10.11%, with J_SC of 17.05 mA cm^-2 and FF of 62.89%; P3TCO-1:PC₇₁ BM-based device gives a PCE of 6.67% with J_SC of 12.31 mA cm^-2 and FF of 58.00%. When the two acceptors of ITIC and PC₇₁ BM are combined, the twisted P3TCO-1-based ternary PSCs exhibit a significantly boosted PCE of up to 11.41%, with a simultaneously improved J_SC of 18.16 mA cm^-2 and FF of 66.78%. These results can guide the improvement of PCE for twisted conjugated polymer-based PSCs.