Highly efficient inverted ternary organic solar cells with polymer fullerene-free acceptor as a third component material

Ternary organic solar cells (OSCs) are fabricate using a single wide-bandgap poly[(2,6-(4,8-bis(5-(2-ethylhexyl) thiophen-2-yl)-benzo [1,2-b:4,5-b0]dithiophene))-alt- (5,5-(10, 30-di-2-thi enyl-50,70-bis(2-e thylhexyl)benzo [10,20-c:40,50-c0]clithiophene-4,8-dione))] (PBDB-T) as the donor material and 3,9-bis (2-methylene-(3-(1,1-dicyanomethylene)-indanone)-5,5,11,11-tetralcis (4-hexylphenyl)-dithieno [2,3-d:2', 3'-d']-s-indaceno[1,2-b:5,6-b']dithiophene) (ITIC) as the acceptor and poly[[N,N'-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-(3,3'-difluoro-2,2'-bithiophene)-5,5'-diyl] (F-N2200) as third component materials. Due to the strong absorption ability at the short-wavelength region. The best power conversion efficiency (PCE) of 10.9% is achieve for the OSCs via incorporating 10 wt% F-N2200 in blend-acceptor materials, with an enhance the short-circuit current (J(SC)) of 17.6 mA cm(-2), fill factor (FF) of 68.0% and stable open-circuit voltage (V-OC) of 0.91 V relative to binary OSCs. The short-wavelength absorption windows of F-N2200 is favourable the harvesting of as many as possible photons and the enhance exciton dissociation ratio at the ITIC/F-N2200 interface due to the deeper LUMO energy level of F-N2200 relative to MC molecule. Meanwhile, the incorporation small amount of F-N2200 is weaken monomolecular recombination and bimolecular recombination under open circuit and short-circuit conditions respectively and enhance the charge carrier mobility. The use of PBDB-T as donor and the blend of MC and F-N2200 as an electron acceptor provides a useful strategy for exploring high-performance ternary OSCs.