Ternary MEH-PPV-CuInS2/ZnO solar cells with tunable CuInS2 content

• Composites with various weight ratios of CuInS2 QDs and polymer (R) are prepared.
• Solar cells are fabricated with composites and vertically aligned ZnO nanorods.
• Solar cells display improved device performance with the dependence on R.
• Modification of ZnO with CuInS2 QDs contributes to increased device performance.
• Composites offer additional absorption, interfaces and channels for improved Jsc.

The paper reports novel ternary MEH-PPV-CuInS2/ZnO solar cells fabricated by incorporating CuInS2 quantum dots (QDs) into pristine MEH-PPV as light-harvester and vertically aligned ZnO nanorod array as electron acceptor. Results show that, MEH-PPV-CuInS2/ZnO solar cells exhibit increased photovoltaic performance compared to MEH-PPV/ZnO devices and the performance dependent on the weight ratio (R) between CuInS2 and MEH-PPV, resulting in a peak power conversion efficiency of 2.48% for R = 0.6 at 15.85 mW/cm2 monochromatic illumination. It is revealed that the increased Jsc is due to the improved light-harvesting, additional MEH-PPV/CuInS2 interfaces for exciton dissociation, and the formation of CuInS2 channels for effective charge transport, while the increased Voc and the decreased charge recombination are attributed to the modification of ZnO surface by CuInS2 QDs which reduces the surface defect concentration of ZnO. However, the decreased Jsc, Voc at too high R value are attributed to the serious aggregations of CuInS2 QDs resulting in the inorganic nanocrystals not well dispersed in organic matrix.