By adding appropriate proportions of nitrobenzene (C 6 H 5 NO 2 ) to the blended solution of poly{[4,8‐bis‐(2‐ethyl‐hexyl‐thiophene‐5‐yl)‐benzo[1,2‐b:4,5‐b′]dithiophene‐2,6‐diyl]‐ alt ‐[2‐(2′‐ethyl‐hexanoyl)‐thieno[3,4‐b]thiophen‐4,6‐diyl]}:[6,6]‐phenyl‐C71‐butyric acid methyl ester (PBDTTT‐C‐T: PC 71 BM), we substantially improved the power conversion efficiency from the best reported value of 7.48–8.88%. Experiments and simulations show that nitrobenzene and PBDTTT‐C‐T form stable coplanar charge‐transfer complexes through hydrogen bonds. Formation of the PBDTTT‐C‐T‐C 6 H 5 NO 2 complex simultaneously increases the external quantum efficiency. The underlying mechanisms of increased external quantum efficiency are attributed to the following: (i) higher lowest unoccupied molecular orbital (LUMO) of PBDTTT‐C‐T‐C 6 H 5 NO 2 for more efficient photoinduced electron transfer to the LUMO of PC 71 BM and (ii) efficient quenching of fluorescence in the active layers due to formation of the PBDTTT‐C‐T‐C 6 H 5 NO 2 complex. This discovery clearly illustrates the potential of hydrogen‐bonded complexes as a new route for efficient polymer‐based photovoltaic devices. Copyright © 2014 John Wiley & Sons, Ltd. Nitrobenzene and PBDTTT‐C‐T form stable coplanar charge‐transfer complexes through hydrogen bonds. Formation of the PBDTTT‐C‐T‐C 6 H 5 NO 2 complex simultaneously increases the external quantum efficiency. The underlying mechanisms of increased external quantum efficiency are attributed to the following: (i) higher lowest unoccupied molecular orbital (LUMO) of PBDTTT‐C‐T‐C 6 H 5 NO 2 for more efficient photoinduced electron transfer to the LUMO of PC 71 BM and (ii) efficient quenching of fluorescence in the active layers due to the formation of PBDTTT‐C‐T‐C 6 H 5 NO 2 complex.


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    Title :

    Formation of charge‐transfer complexes significantly improves the performance of polymer solar cells based on PBDTTT‐C‐T: PC71BM



    Published in:

    Publication date :

    2015




    Type of media :

    Article (Journal)


    Type of material :

    Print


    Language :

    English



    Classification :

    BKL:    53.36 Energiedirektumwandler, elektrische Energiespeicher