Ruiping Qin, Yurong Jiang, Heng Ma
Sep 5, 2013
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0
Influential Citations
10
Citations
Journal
Journal of Applied Polymer Science
Abstract
Planar conjugated 2,7-linked carbazole blocks: Q1(2,7-dibromo-9-octyl-9H-carbazole); Q2(7,7 0 -dibromo-9,9 0 -dioctyl- 9H,9 0 H-2,2 0 -bicarbazole); Q3 (7-bromo-7 0 -(7-bromo-9-octyl-9H-carbazol-2-yl)-9,9 0 -dioctyl-9H,9 0 H-2,2 0 -bicarbazole) were coupled with same acceptor (4,7-di(2,5-thiophene)-5,6-dioctyloxy-2,1,3-Benzothiadiazole) to prepare polymers HXS-1, 2, 3 (Scheme 1). Bulk- heterojunction polymer solar cells (BHJ PSCs) with these polymers were made. Power conversion efficiency of HXS-1 was proved to be over 5.4%. It declined dramatically to 0.43% and 0.23% for HXS-2 and 3 respectively. Their absorption and X-ray diffraction pat- tern show the torsion angle in main chain increased when more carbazole units were added. More carbazoles will make polyconden- sation reaction more difficult to get high molecular weight polymers. The torsion angle was calculated using a semiempirical molecu- lar orbital method. All the results pointed out that the coplanarity in the conjugated backbone was destroyed. Electron delocalization was disturbed because p-orbital overlapping only occurs effectively in the parallel orbit so charge cannot move a longer distance. This study offers a useful and important insight to designing polymers for high performance PSCs. V C 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 129: 2671-2678, 2013