Tuning the Morphological and Optical Characteristics of PCDTBT:PC71BM Blends via Fullerene Ratio Adjustment

Abstract

     Morphological and optical features of the PCDTBT:PC71BM combination of varying concentrations of PC71BM are the subject of this paper in the pursuit of optimizing their use in the organic photovoltaic (OPV) devices. It was deposited as thin films in different ratios of (1:0, 1:1, 1:2, 1:3 and 1:4 w/w) of PCDTBT: PC71BM onto pre-cleaned glass bases using spin-coating technique. The XRD shapes of all the prepared thin films at multiple PC71BM concentrations have a broad peak at about 23 ͦ, which suggests that they are amorphous. To examine the surface morphology of the thin films, FESEM was employed. The findings indicated that an increase in PC71BM concentrations resulted in formation of visible clusters on the outer layer. The UV-visible absorption spectra were taken, and two major peaks of pure PCDTBT were observed at about 394 nm and 557 nm. When varying PC71BM concentrations were introduced, there were slight changes in the absorption peaks, blue shift. This conveys morphological and optical changes. These results indicate that the fullerene ratio can be tuned to have a strong effect on the blend characteristics, and this will be a viable way of improving the working characteristics of PCDTBT:PC71BM-based OPV devices.