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Keywords:

  • heterojunctions;
  • hybrid materials;
  • metal xanthate;
  • nanomorphology;
  • organic electronics;
  • polymer semiconductors;
  • solar cells

ABSTRACT

This contribution presents the correlation between structural, morphological, and fluorescence properties as well as device performance of nanocomposite solar cells comprising two low-band gap polymers, poly[[9-(1-octylnonyl)−9H-carbazole-2,7-diyl]-2,5-thiophenediyl-2,1,3-benzothiadiazole-4,7-diyl-2,5-thiophenediyl] (PCDTBT) and poly[2,1,3-benzothiadiazole-4,7-diyl-2,5-thiophenediyl(9,9-dioctyl-9H-9-silafluorene-2,7-diyl)−2,5-thiophenediyl] (PSiF-DBT) and copper indium sulfide (CIS). It shows that, in analogy to organic solar cells, the device efficiency is strongly determined by different polymer structures leading to a different packing of the polymer chains and consequently to diverse morphologies. X-ray diffraction investigation indicates increased semicrystallinity in PSiF-DBT compared with the nitrogen analogue PCDTBT. The photoluminescence (PL) quenching of this polymer indicates that the higher photogeneration achieved in PSiF-DBT based films can be correlated to a favorable donor-acceptor phase separation. Transmission electron microscopy studies of PCDTBT:CIS blended films suggest the formation of polymer agglomerates in the layer resulting in a decreased PL quenching efficiency. For the considered polymer:CIS system, the combination of these effects leads to an enhanced overall device efficiency. © 2013 Wiley Periodicals, Inc. J. Polym. Sci. Part B: Polym. Phys. 2013, 51, 1400–1410