1192352-10-5Relevant articles and documents
Correlation of intermolecular packing distance and crystallinity of D-A polymers according to π-spacer for polymer solar cells
Lee, Tae Ho,Choi, Min Hee,Jeon, Sung Jae,Moon, Doo Kyung
, p. 756 - 766 (2016)
Donor–acceptor-type polymers, PBDPBT-T, PBDPBT-TT, and PBDPBT-biT, were polymerized via Stille coupling reactions. In the unfavorable mode of DFT calculations, the distance between BDP in the two different polymer main chains showed different distance of repeating unit (Dn) according to the π-spacers type. Especially, PBDPBT-TT caused larger D2 than PBDPBT-T and PBDPBT-biT. The UV–vis absorption spectra of PBDPBT-T and PBDPBT-biT films were red-shifted compared with the solution absorption, whereas that of a PBDPBT-TT film was blue-shifted. PBDPBT-T and PBDPBT-biT had high crystallinity and a tendency of face-on orientation. In contrast, PBDPBT-TT had low crystallinity. Owing to differences in packing formation, the polymers had different JSC values. When a polymer solar cell device was fabricated through a solution process, PBDPBT-biT (in a 1:1.5 ratio with PC70BM) exhibited a PCE of 4.50%, with a JSC value of 8.6?mA/cm2, a VOC value of 0.88?V, and an FF value of 59.4%.
Chain length dependence of the photovoltaic properties of monodisperse donor-acceptor oligomers as model compounds of polydisperse low band gap polymers
Zhou, Cheng,Liang, Yamin,Liu, Feng,Sun, Chen,Huang, Xuelong,Xie, Zengqi,Huang, Fei,Roncali, Jean,Russell, Thomas P.,Cao, Yong
, p. 7538 - 7547 (2014)
Well-defined conjugated oligomers (Sn) containing from 1 to 8 units of a tricyclic building block involving a dioctyloxybenzothiadiazole unit with two thienyl side rings (S1) are synthesized by a bottom-up approach. UV-Vis absorption data of solutions show that chain extension produces a narrowing of the HOMO-LUMO gap (Δ E) to values slightly smaller than that of the parent polymer (P1). Plots of Δ E and of the band gap of films (E g) versus the reciprocal chain length show that Δ E and Eg converge towards a limit corresponding to an effective conjugation length (ECL) of 7-8 S1 units. UV-Vis absorption and photoluminescence data of solutions and solid films show that chain extension enhances the propensity to inter-chain aggregation. This conclusion is confirmed by GIXD analyses which reveal that the edge-on orientation of short-chain systems evolves toward a face-on orientation as chain length increases while the stacking distance decreases beyond 7 units. The results obtained on solution-processed BHJ solar cells show a progressive improvement of power conversion efficiency (PCE) with chain extension; however, the convergence limit of PCE remains inferior to that obtained with the polymer. These results are discussed with regard to the role of mono/ polydispersity and chain aggregation.
Improved bulk-heterojunction polymer solar cell performance through optimization of the linker groupin donor-acceptor conjugated polymer
Sun, Ying,Lin, Baoping,Yang, Hong,Gong, Xiaohui
, p. 1535 - 1542 (2012)
Two donor-acceptor conjugated polymers PCTBTC8 and PCTTBTC12 have been prepared from Suzuki coupling reactions between the 2,7-carbazole and alkoxy substituted 2,1,3-benzothiadiazole units with two different linker groups thiophene and thieno[3,2-b] thiophene, respectively. The polymer PCTTBTC12 with the thieno thiophene linker group possessed a red-shifted UV-vis absorption spectrum and similar HOMO level in comparison with PCTBTC8. BHJ polymer solar cells were fabricated to investigate the photovoltaic properties of the two polymers and the polymer PCTTBTC12 showed superior device performance than PCTBTC8 with a significantly improved current density. In addition, the hole only devices tests results indicated that the hole mobility of the polymer was increased by replacing the thiophene group with fused thieno thiophene as the linker. The relationships between the device performance with the light absorption, energy levels, BHJ film morphology and hole mobility are discussed in details. And the improved photovoltaic property of the polymer PCTTBTC12 probably can be contributed to the better light absorption spectrum and enhanced hole transporting ability related to the more electron rich nature and planar structure of the thieno[3,2-b] thiophene group.
D-π-A-π-D type benzothiadiazole-triphenylamine based small molecules containing cyano on the π-bridge for solution-processed organic solar cells with high open-circuit voltage
Zeng, Shaohang,Yin, Lunxiang,Ji, Changyan,Jiang, Xueying,Li, Kechang,Li, Yanqin,Wang, Yue
, p. 10627 - 10629 (2012/11/07)
Two novel D-π-A-π-D structured small molecules composed of benzothiadiazole and triphenylamine were designed and synthesized. BDCTBT with cyano on the π-bridge exhibited a deep HOMO energy level, resulting in an impressive VOC of up to 1.04 V with a PCE of 3.85%, while non-cyano substituted BDETBT yielded a VOC of 0.94 V and a PCE of 1.99%.