Impact of helical organization on the photovoltaic properties of oligothiophene supramolecular polymersElectronic supplementary information (ESI) available: Synthesis and characterization of 3 and 4, UV-vis spectra, solar cell device properties and AFM images. See DOI: 10.1039/c7sc05093c

• Main Authors: Ouchi, Hayato, Kizaki, Takahiro, Yamato, Masaki, Lin, Xu, Hoshi, Nagahiro, Silly, Fabien, Kajitani, Takashi, Fukushima, Takanori, Nakayama, Ken-ichi, Yagai, Shiki
• Format: Article
• Language: English
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/c7sc05093c

Helical self-assembly of functional π-conjugated molecules offers unique photochemical and electronic properties in the spectroscopic level, but there are only a few examples that demonstrate their positive impact on the optoelectronic device level. Here, we demonstrate that hydrogen-bonded tapelike supramolecular polymers of a barbiturated oligo(alkylthiophene) show notable improvement in their photovoltaic properties upon organizing into helical nanofibers. A tapelike hydrogen-bonded supramolecular array of barbiturated oligo(butylthiophene) molecules was directly visualized by STM at a liquid-solid interface. TEM, AFM and XRD revealed that the tapelike supramolecular polymers further organize into helical nanofibers in solution and bulk states. Bulk heterojunction solar cells of the helical nanofibers and soluble fullerene showed a power conversion efficiency of 4.5%, which is markedly high compared to that of the regioisomer of butyl chains organizing into 3D lamellar agglomerates. Higher order structures of semiconducting supramolecular polymers have a huge impact on their BHJ-OPV device performance.