title: Bilayer order in a polycarbazole-conjugated polymer.
abstract: One of the best performing semiconducting polymers used in bulk heterojunction devices is PCDTBT, a polycarbazole derivative with solar-conversion efficiencies as high as 7.2%. Here we report the formation of bilayer ordering in PCDTBT, and postulate that this structural motif is a direct consequence of the polymer's molecular design. This bilayer motif is composed of a pair of backbones arranged side-to-side where the alkyl tails are on the outer side. This is in stark contrast to the monolayer ordering found in other conjugated polymers. The crystalline bilayer phase forms at elevated temperatures and persists after cooling to room temperature. The existence of bilayer ordering, along with its high-packing fraction of conjugated moieties, may guide the synthesis of new materials with improved optoelectronic properties.
authors.affiliation: Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
authors.forename: Xinhui
authors.initials: X
authors.lastname: Lu
authors.forename: Htay
authors.initials: H
authors.lastname: Hlaing
authors.forename: David S
authors.initials: DS
authors.lastname: Germack
authors.forename: Jeff
authors.initials: J
authors.lastname: Peet
authors.forename: Won Ho
authors.initials: WH
authors.lastname: Jo
authors.forename: Denis
authors.initials: D
authors.lastname: Andrienko
authors.forename: Kurt
authors.initials: K
authors.lastname: Kremer
authors.forename: Benjamin M
authors.initials: BM
authors.lastname: Ocko