Highly porous nanostructured polyaniline/carbon nanodots as efficient counter electrodes for Pt-free dye-sensitized solar cells

We report a novel method for synthesizing highly porous polyaniline (PANI) using carbon nanodots (CNDs) as a nucleating agent and demonstrate their use as counter electrodes (CEs) for dye-sensitized solar cells (DSSCs). CNDs surrounded with aniline act as efficient nuclei in the polymerization reaction. CNDs disrupt undesirable secondary growth reactions leading to the formation of an agglomerated structure, and organize the highly porous PANI structures with a large surface area (43.6 m2 g−1). Moreover, the presence of CNDs in the polymerization mixture facilitates generation of head-to-tail dimers, and enhances the degree of para-coupling in the molecular structure of PANI. As a result of these nucleation effects, the fabricated PANI-CND films exhibit an increased electrical conductivity of ca. 774 S cm−1. When used as a CE in DSSCs, PANI-CND CEs exhibit a superior power conversion efficiency (η = 7.45%) to those of conventional platinum (η = 7.37%) and pristine PANI CEs (η = 5.60%).