Photocrosslinkable liquid-crystalline polythiophenes with oriented nanostructure and stabilization for photovoltaics
Photocrosslinkable liquid-crystalline polythiophenes with oriented nanostructure and stabilization for photovoltaics
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DOI：
10.1016/j.orgel.2011.10.012
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发表时间：
2012
影响因子：
3.2
通讯作者：
Xuee Li;Lie Chen;Yiwang Chen;Fan Li;Kai Yao
中科院分区：
文献类型：
--
作者：
Xuee Li;Lie Chen;Yiwang Chen;Fan Li;Kai Yao
A novel stable and photocrosslinkable electron-donor material, liquid-crystalline polythiophene containing cyano-biphenyl mesogenic pendant, namely, poly{3-[6-(4′-cyano-biphenyloxy)hexyl]thiopheneylenethiophene-alt-3-(6-bromohexyl)thiophene} (PTcbpTT), was designed and synthesized. The structural anisotropy originating from cyano-biphenyl mesogens can induce the PTcbpTT to assemble into a well ordered morphology and consequently lead to the red-shift absorption, enhanced photoluminescence. The thermal treatment drives further development of the morphology of the copolymer and its blend films mixed with [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), towards a state of microphase separation in the nanometer scale. Furthermore, the bulk heterojunction devices based on the PTcbpTT:PCBM (1:1wt.%) active layer have been constructed. Without extensive optimization, the LC annealing device yields an enhancement of power conversion efficiency from 0.5% to 1.2%, showing a significantly increased Jscand FF with respect to its untreated counterpart, thanks to the ordered microphase separation channels for charge transportation. The high Vocvalue of 0.731V is due to the low HOMO level of PTcbpTT. Unlike devices prepared from PTcbpTT:PCBM blend without UV treatment, photocrosslinked PTcbpTT:PCBM devices are stable even when annealed for two days at the elevated temperature of 150°C, implying that the photocrosslinked structure dramatically suppresses largescale phase segregation.
