High-efficiency hole extraction/electron-blocking layer to replace poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) in bulk-heterojunction polymer solar cells

An anode interfacial layer is reported for bulk-heterojunction (BHJ) polymer solar cells to replace the commonly used poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS). A poly9,9-dioctylfluorene-co-N-[4-(3-methylpropyl)-diphenylamine] (TFB)+4,4′-bis(p-trichlorosilylpropylphenyl)phenylaminobiphenyl (TPDSi2) blend is crosslinked, forming robust ∼10nm thick films covalently bound to indium tin oxide, which transport holes while blocking misdirected electrons. The thermal stability and photovoltaic performance metrics of TFB:TPDSi2-modified BHJ cells are significantly greater than those of cells fabricated in parallel with PEDOT:PSS or with no interfacial layer. For a poly2-methoxy-5-(3′,7′-dimethyloctyloxyl-1,4-phenylene vinylene: methanofullerene6 6-phenyl C61-butyric acid methyl ester cell, Voc=0.89V, Jsc=4.62mA∕cm2, FF=54.4%, and ηp=2.23%.