1160823-85-7Relevant articles and documents
The effect of photocrosslinkable groups on thermal stability of bulk heterojunction solar cells based on donor-acceptor-conjugated polymers
Chen, Xun,Chen, Lie,Chen, Yiwang
, p. 4156 - 4166 (2013)
Three different types of photocrosslinkable groups into a low band-gap donor-acceptor-conjugated polymer, namely poly{benzo[1,2-b:4,5-b′] dithiophene-alt- thieno[3,4-b]thiophene} (PBT), were developed to comparatively investigate the effect of the photocrosslinkable groups on the thermal stability of bulk heterojunction solar cells. Compared with vinyl groups, bromine- and azide- photocrosslinkable groups are more prompt for photocrosslinking to yield a denser crosslinking network, probably due to the different crosslinking mechanisms and reaction rates. In contrast to the reference device decreasing to less than 10% of its initial efficiency value after 80 h of annealing at 150 °C, a great improvement in the thermal stability of performance of all these crosslinked functional copolymers devices demonstrates that photocrosslinking can effectively improve the thermal stability of the active layer by suppressing [6,6]-phenyl-C61-butyric acid methyl diffusion and phase separation. Furthermore, the solar cells with crosslinked bromine- and azide-functionalized PBT polymers showed very thermally stable photovoltaic device performance by retaining 78 and 66% of their initial device efficiency, respectively, whereas vinyl-functionalized PBT devices retained only 51% of its initial value after long-time thermal annealing. This suggests that an appropriate crosslinking network with homogenous active morphology could dramatically enhance the device stability without sacrificing the performance.
Synthesis and characterization of thieno[3,4-b]thiophene-based copolymers bearing 4-substituted phenyl ester pendants: Facile fine-tuning of homo energy levels
Yamamoto, Tomoyuki,Ikai, Tomoyuki,Kuzuba, Mitsuhiro,Kuwabara, Takayuki,Maeda, Katsuhiro,Takahashi, Kohshin,Kanoh, Shigeyoshi
scheme or table, p. 6659 - 6662 (2012/03/26)
A study was conducted to design and synthesize PTB-based polymers bearing 4-substituted phenyl esters in place of the alkyl esters as the pendants of the thieno[3,4-b]thiophene (TT) unit. It was found that their highest occupied molecular orbital (HOMO) energy levels were readily fine-tuned by changing the substituents on the phenyl groups. Four novel TT monomers bearing various phenyl ester groups (TT1-TT4) were easily prepared in one pot from commercially available phenol derivatives and the key precursor compound, 4,6-dibromothieno[3,4-b]thiophene-2-carboxylic acid, which was synthesized by modified literature procedures. The molecular weights of the obtained polymers were determined by size-exclusion chromatography (SEC) in tetrahydrofuran (THF). The thermal stability of these polymers was investigated by thermal gravimetric analysis (TGA) under a nitrogen atmosphere. The results show that all polymers have good thermal stability with 5% weight loss temperatures (Td) above 300 °C, which is adequate for application in PSC devices.
