Photocrosslinkable liquid-crystalline polymers for stable photovoltaics by adjusting side-chains spacing and fullerene size to control intercalation

详细信息	查看全文 | 推荐本文 |

• 作者：Kai Yao^a ; ¹ ; Lie Chen^a ; ^b ; ¹ ; Ting Hu^a ; ^b ; Yiwang Chen^a ; ^b ; ^{ywchen@ncu.edu.cn}
• 关键词：Photovoltaics ; Liquid crystals ; Conjugated polymers ; Photo-crosslink
• 刊名：Organic Electronics
• 出版年：2012
• 期刊代码：137_15661199
• 类别：et
• 出版时间：August, 2012
• 卷：13
• 期：8
• 页码：1443-1455
• 文件大小：2156 K

摘要

We report a novel copolymer system with high crystallinity and photocrosslinkable building blocks for 蟺-蟺 intermolecular interactions that is, an alternating copolymer with liquid-crystalline nature, and heat/solvent resistance. By copolymerization of 2,5-bis(3-bromododecylthiophen-2-yl)thieno[3,2-b]thiophene (BbTTT) monomer with thiophene and thieno[3,2-b]thiophene via Stille reaction, two novel copolymers PBbTTT-T and PBbTTT-TT have been synthesized. The balanced space between fullerene size and the side-chains of the polymer is crucial to determine the optimum polymer:fullerene blending ratios and the formation of intercalated nanostructure, in which the lamellar arrangement can be controlled by adjusting the fullerene size. This pre-optimum bimolecular crystal morphology can be frozen and preserved with long term performance after UV treatment, a clear advantage for the photo-crosslinking strategy. Furthermore, the free space in the intercalation impacts greatly on the stability of the donor-acceptor bicontinuous network, especially after photocrosslinking. The bulk-heterojunction organic photovoltaics based on PBbTTT-TT:PC₇₁BM at 1:3.5 by weight shows an stable, well-ordered and intercalated nanostructure with an efficiency higher than 2.4%after 40 h annealing at an elevated temperature of 150 掳C.