A new conjugated polymer, PDTTTPD, comprising 2,5-di(thiophen-2-yl)thieno[3,2-b]thiophene and thieno[3,4-c]pyrrole-4,6-dione units, exhibits high crystallinity and excellent thermal stability. A device incorporating PDTTTPD and [6,6]-phenyl-C71-butyric acid methyl ester (1 : 1, w/w) exhibited a power conversion efficiency of 5.1%.
![Graphical abstract: Crystalline conjugated polymer containing fused 2,5-di(thiophen-2-yl)thieno[2,3-b]thiophene and thieno[3,4-c]pyrrole-4,6-dione units for bulk heterojunction solar cells](http://hg.y866.cn/compound/lib/scimg/usr/1/C1CC10585J.jpg)
