title: Enhancing the thermal stability of polythiophene:fullerene solar cells by decreasing effective polymer regioregularity.
abstract: Regioregularity has been shown to be an important aspect for the properties of poly(3-hexylthiophene) both in the pristine material and in bulk heterojunction photovoltaics with the fullerene derivative PCBM. Here we present a straightforward method to adjust the effective regioregularity of poly(3-hexylthiophene) by introducing 3,4-dihexylthiophene into the polymer chain. By investigating bulk heterojunction morphology and photovoltaic performance upon annealing, we observe that polythiophene with 91% regioregularity maintains equivalent electronic properties but forms a more thermally stable interpenetrating network with PCBM than polythiophene with regioregularity >96%.
authors.affiliation: Departments of Chemistry and Chemical Engineering, University of California-Berkeley, 718 Latimer Hall, Berkeley, CA 94720-1460, USA.
authors.forename: Kevin
authors.initials: K
authors.lastname: Sivula
authors.forename: Christine K
authors.initials: CK
authors.lastname: Luscombe
authors.forename: Barry C
authors.initials: BC
authors.lastname: Thompson
authors.forename: Jean M J
authors.initials: JM
authors.lastname: Fréchet