Dependence of crystallite formation and Preferential Backbone Orientations on the Side Chain Pattern in PBDTTPD Polymers

А. El Labban, J. Warnan, C. Cabanetos, O. Ratel, C.J. Tassone, M.F. Toney and P.M. Beaujuge
ACS Applied Materials and Interfaces, 6(22), 19477-19481, (2014)

Dependence of crystallite formation and Preferential Backbone Orientations on the Side Chain Pattern in PBDTTPD Polymers

Keywords

Side chain,  Benzo[1,2-b:4,5-b]dithiophene,  Thieno[3,4-c]pyrrole-4,6-dione,  -conjugated polymers,  Polymer crystallite, Backbone orientation

Abstract

​Alkyl substituents appended to the π-con-jugated main chain account for the solution-processability and film-forming properties of most π -conjugated polymers for organic electronic device applications, including field-effect transistors (FETs) and bulk heterojunction (BHJ) solar cells. Beyond film-forming properties, recent work has emphasized the determining role that side chain substituents play on polymer self-assembly and thin- film nanostructural order, and, in turn, on device performance. However,the factors that determine polymer crystallite orientation in thin- films, implying preferential backbone orientation relative to the device substrate, are a matter of some debate, and these structural changes remain difficult to anticipate. In this report, we show how systematic changes in the side-chain pattern of poly(benzo[1,2-b:4,5 -b′]dithiophene−alt−thieno[3,4-c]pyrrole-4,6-dione)(PBDTTPD) polymers can (i) influence the propensity of the polymer to order in the π-stacking direction, and (ii) direct thepreferential orientation of the polymer crystallites in thin films (e.g.,“face-on”vs“edge-on”). Oriented crystallites, specificallycrystallites that are well-ordered in the π-stacking direction, are believed to be a key contributor  to improved thin-film device performance in both FETs and BHJ solar cells.

Code

DOI: 10.1021/am505280a

Sources

Website PDF

See all publications 2014