Effect of Backbone Regioregularity on the Structure and Orientation of a Donor鈥揂cceptor Semiconducting Copolymer

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• 作者：Louis A. Perez ; Peter Zalar ; Lei Ying ; Kristin Schmidt ; Michael F. Toney ; Thuc-Quyen Nguyen ; Guillermo C. Bazan ; Edward J. Kramer
• 刊名：Macromolecules
• 出版年：2014
• 出版时间：February 25, 2014
• 年：2014
• 卷：47
• 期：4
• 页码：1403-1410
• 全文大小：480K
• 年卷期：v.47,no.4(February 25, 2014)
• ISSN：1520-5835

文摘

A regioregular (RR) donor鈥揳cceptor conjugated copolymer based on cyclopenta[2,1-b:3,4-b鈥瞉dithiophene (CDT) and pyridal[2,1,3]thiadiazole (PT) structural units was prepared by using polymerization reactions involving reactants specifically designed to avoid random orientation of the asymmetric PT heterocycle along the copolymer backbone. Compared to its regioirregular (RI) counterpart, the RR polymer exhibits a 2 orders of magnitude increase in hole mobility from 0.005 to 0.6 cm² V^鈥? s^鈥?. To probe the reason for this difference in mobility, we examined the crystalline structure and its orientation in thin films of both copolymers as a function of depth via grazing incidence wide-angle X-ray scattering (GIWAXS). In the RI film, the 蟺鈥撓€ stacking direction of the crystallites is mainly perpendicular to the substrate normal (edge-on orientation) while in the RR film the crystallites adopt a mixed 蟺鈥撓€ stacking orientation in the center of the film as well as near the interface between the polymer and the dielectric layer. These results demonstrate that control of backbone regularity is another important design criterion to consider in the synthesis and optimization of new conjugated copolymers with asymmetric structural units.