The effect of processing additive on aggregated fullerene derivatives in bulk-heterojunction polymer solar cells

The effects of processing additive on fullerene aggregation in polymer BHJ solar cells were investigated using new fullerene derivatives bearing a thiophene moiety and alkyl groups. Although new fullerene derivatives showed quite similar electronic transport properties in field-effect transistors, the photovoltaic performances were significantly limited by their aggregative nature. Processing with 1% CN additive, however, changed the aggregated morphology of BHJ films to a smoother and homogeneous morphology, improving photovoltaic performance. The result indicates that processing additive not only influences on polymer side, but also significantly affects fullerene acceptor component.

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► New fullerene derivatives showed similar electronic properties to PCBM.
► Chloronaphthalene additive changed the aggregated morphology to homogeneous.
► Improved morphology induces enhanced performance of solar cells and bipolar FETs.
► Processing additive also can significantly affect on fullerene acceptor component.