Butterfly nanostructures via regioregularly grafted multi‐walled carbon nanotubes and poly(3‐hexylthiophene) to improve photovoltaic characteristics

Abstract

Abstract Butterfly nanostructures were designed using multi‐walled carbon nanotubes (CNTs) grafted with regioregular poly(3‐hexylthiophene) (RR‐P3HT) chains (CNT‐ graft ‐P3HT). The secondary crystallization of RR‐P3HT free chains onto CNT‐ graft ‐P3HT reflected the donor–acceptor supramolecules with a butterfly configuration, in which the CNT acted as the body of the butterfly and seeded crystallization of P3HT free chains resulted in the wings having a width of 37–38 nm. Butterfly supramolecules demonstrated high melting point (241.2 °C), fusion enthalpy (31.5 J g −1 ) and crystallinity (85.13%). High photoluminescence quenching and thus donating–accepting property were also detected for the butterfly nanohybrids with a bandgap energy of 1.94 eV. Incorporation of butterfly nanostructures in the active layer of photovoltaic devices (P3HT:butterfly) conspicuously affected the system characteristics including short circuit current density ( J sc ; 10.84 mA cm −2 ), fill factor (FF; 56%) and power conversion efficiency (PCE; 3.94%). The inclusion of phenyl‐C71‐butyric acid methyl ester molecules as second acceptor in thin‐film active layers further increased the efficacy of systems, i.e. J sc of 12.23 mA cm −2 , FF of 63%, open circuit voltage of 0.66 V and PCE of 5.08%, without considering external treatments and additives. © 2018 Society of Chemical Industry