Benzodithiophene-based two-dimensional polymers with extended conjugated thienyltriphenylamine substituents for high-efficiency polymer solar cells

Fan, Qunping; Liu, Yu; Yang, Pingao; Su, Wenyan; Xiao, Manjun; Chen, Jianhua; Li, Min; Wang, Xiangdong; Tan, Hua; Yang, Renqiang; Zhu, Weiguo

doi:10.1016/j.orgel.2015.04.013

Cited by 16 publications

(4 citation statements)

References 44 publications

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“…Moreover, the absorption intensity of the second absorption band increased upon increasing the content of DFBT units in the copolymer, both in solution and in the thin film state. In addition, the red-shifts and full widths at halfmaximum of the absorption bands of the copolymers in the films were greater than those in solution, presumably because of strong noncovalent interactions (e.g., π-stacking) between the polymer backbones and conjugated pendant units [30,51]. Notably, the spectra of PBTFA11 in solution and as a thin film exhibited an additional shoulder peak in the range from 680 to 780 nm.…”

Section: Results and Discussion 31 Characterization Of Ptsmentioning

confidence: 96%

“…We attribute the first absorption band in the range 325-500 nm to the n-* transitions of the conjugated side chains and the -* transitions of the conjugated main chain [29]. The second absorption band in the range 500-800 nm originated from intramolecular charge transfer (ICT) between the thiophene derivative-based donor units and the DFBT-based acceptor units [30]. Moreover, the absorption intensity of the second absorption band increased upon increasing the content of DFBT units in the copolymer, both in solution and in the thin film state.…”

Section: Results and Discussion 31 Characterization Of Ptsmentioning

confidence: 97%

“…Triphenylamine (TPA) derivatives are among the most popular electron-donor groups because of their good electron-donating and hole-transporting performance, and good solubility in organic solvents [29,30]. Fan et al [30] reported two benzodithiophene-based 2-D polymers featuring extended conjugated thienyltriphenylamine substituents; polymers presenting these extended TPA-based conjugated pendants exhibited good thermal, photophysical, and photovoltaic performance.…”

Section: W H Lee 1 B T Liu 2 R H Leementioning

confidence: 99%

“…Many BT-based conjugated polymers providing good PV performance have been synthesized through the copolymerization of BT units with various electron-donating groups (e.g., benzodithiophene, dithienosilole, 4H-cyclopenta [2,1-b;3,4-b′]dithiophene) [33][34][35]. Furthermore, incorporating fluorine atoms at the 5-and 6-positions of the BT unit can lower the energy levels of the lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) of the resulting conjugated polymers, resulting in PSCs displaying higher open-circuit voltages; higher hole mobility is also obtained because of stronger intermolecular interactions among the polymer chains [30,[36][37][38]. The PV performance of difluorobenzothiadiazole (DFBT)-based polymers is usually superior to that of BT-based polymers [39][40][41].…”

Section: W H Lee 1 B T Liu 2 R H Leementioning

confidence: 99%

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Difluorobenzothiadiazole based two-dimensional conjugated polymers with triphenylamine substituted moieties as pendants for bulk heterojunction solar cells

Lee¹,

Liu²,

李榮和³

et al. 2017

Express Polym. Lett.

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Abstract. Three donor/acceptor (D/A)-type two-dimensional polythiophenes (PTs; PBTFA13, PBTFA12, PBTFA11) featuring difluorobenzothiadiazole (DFBT) derivatives as the conjugated (acceptor) units in the polymer backbone and tertbutyl-substituted triphenylamine (tTPA)-containing moieties as (donor) pendants have been synthesized and characterized. These PTs exhibited good thermal stabilities, broad absorption spectra, and narrow optical band gaps. The cutoff wavelength of the UV-Vis absorption band was red-shifted upon increasing the content of the DFBT units in the PTs. Bulk heterojunction solar cells having an active layer comprising blends of the PTs and fullerene derivatives [6,6] phenyl-C 61/71 -butyric acid methyl ester (PC 61 BM/PC 71 BM) were fabricated; their photovoltaic performance was strongly dependent on the content of the DFBT derivative in the PT. Incorporating a suitable content of the DFBT derivative in the polymer backbone enhanced the solar absorption ability and conjugation length of the PTs. The photovoltaic properties of the PBTFA13-based solar cells were superior to those of the PBTFA11-and PBTFA12-based solar cells.

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Section: Results and Discussion 31 Characterization Of Ptsmentioning

confidence: 96%

Section: Results and Discussion 31 Characterization Of Ptsmentioning

confidence: 97%

Section: W H Lee 1 B T Liu 2 R H Leementioning

confidence: 99%

Section: W H Lee 1 B T Liu 2 R H Leementioning

confidence: 99%

See 2 more Smart Citations

Difluorobenzothiadiazole based two-dimensional conjugated polymers with triphenylamine substituted moieties as pendants for bulk heterojunction solar cells

Lee¹,

Liu²,

李榮和³

et al. 2017

Express Polym. Lett.

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A New Polythiophene Derivative for High Efficiency Polymer Solar Cells with PCE over 9%

Fan

Guo

et al. 2016

Advanced Energy Materials

Self Cite

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compared with that of [6,6]-phenyl-C 61 -butyric acid methyl ester (PC 61 BM) or [6,6]-phenyl-C 71 -butyric acid methyl ester (PC 71 BM) (−3.90 eV), then the PSCs based on P3HT:IC 70 BA shows the improved PCE of ≈7.4% with increased V oc of 0.87 V compared to the PSCs based on P3HT:PC 71 BM (PCE of ≈4.4% and V oc of 0.61 V).[23] Another strategy is to design and synthesize new PT derivatives with deep HOMO energy level by modification of side chains. [3,25,32,33] For instance, Zhang et. al. synthesized a PT derivative, PDCBT, by attaching electron-withdrawing carboxylate substituents on PT backbone, and the HOMO level of PDCBT (−5.26 eV) decreased by 0.36 eV in comparison with P3HT (−4.90 eV). [25] As a result, the corresponding PSCs showed an enhanced PCE of 7.2% with increased V oc of 0.91 V. In addition, to construct the D-A type PT derivatives by introducing the thiophene-based acceptor units has been proved to be an effective way to modulate the energy levels of PT derivatives. [24,34] The PT derivative PBT1 with the thiophene fused benzodithiophene-4,8-dione (BDD) acceptor unit was reported and showed a lower HOMO level (−5.13 eV), and an improved PCE of 6.88% was achieved with V oc of 0.83 V in the PBT1-based PSCs. [24] More interestingly, this method can simultaneously reduce the bandgap of PT derivatives, resulting in the broadening of absorption, which benefits for increasing J sc and PCE. Therefore, the performance of PSCs based on the PT derivatives with D-A structure still has great room for improvement.Recently, fluorination has attracted much attention due to its multiple effects on the photophysical properties of conjugated polymers, i.e., the strong electron-withdrawing ability of fluorine atom can effectively modulate the energy levels of polymers with minor effect on their bandgaps and induce the strong dipole along C F bond, resulting in the strong inter/ intramolecular interaction which benefits the excitons dissociation and charge carries transport. [35][36][37][38][39][40][41][42][43][44][45] Hence, in this work, we designed and synthesized a novel D-A structured PT derivative, PBDD-ff4T, based on BDD as acceptor unit and difluorinated bithiophene (ff2T) as donor unit. By introducing two strong electron-withdrawing fluorine atoms to the bithiophene unit in the polymer backbone, PBDD-ff4T showed lower HOMO level of −5.42 eV, smaller optical bandgap (E g opt ) of 1.74 eV, and a higher crystallinity compared to the analog polymer PBT1 without fluorine substituent (HOMO = −5.13 eV and E g opt = 1.77 eV). [24] The lower HOMO level and smaller bandgap could be beneficial for improving the V oc and J sc in PSCs. As a result, the PBDD-ff4T/PC 71 BM-based PSCs under optimal conditions exhibit the highest PCE of 9.2% with V oc of 0.95 V, J sc of 13.2 mA cm −2 , and FF of 73%. This value of PCE is one of the highest values reported in the literature so far for the PSCs As a promising next generation energy source technology, the bulk heterojunction (BHJ) polymer solar cells (PSCs) based on conjugated ...

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High‐Performance Wide Bandgap Copolymers Using an EDOT Modified Benzodithiophene Donor Block with 10.11% Efficiency

Feng

Yang

et al. 2017

Advanced Energy Materials

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Newly developed benzo[1,2‐b:4,5‐b′]dithiophene (BDT) block with 3,4‐ethylenedioxythiophene (EDOT) side chains is first employed to build efficient photovoltaic copolymers. The resulting copolymers, PBDTEDOT‐BT and PBDTEDOTFBT, have a large bandgap more than 1.80 eV, which is attributed to the increased steric hindrance between the BDT and EDOT skeletons. Both copolymers possess the satisfied absorptions, low‐lying highest occupied molecular orbital (HOMO) levels and high crystallinity. Using the fluorination strategy, PBDTEDOT‐FBT exhibits a wider and stronger absorption and a deeper HOMO level than those of PBDTEDOT‐BT. PBDTEDOT‐FBT:[6,6]‐Phenyl C71 butyric acid methyl ester (PC71BM) blend also shows the higher hole mobility and better surface morphology compared with the PBDTEDOTBT:PC71BM blend. Combination of above advantages, PBDTEDOT‐FBT devices exhibit much higher power conversion efficiency (PCE) of 10.11%, with an improved open circuit voltage (Voc) of 0.86 V, short circuit current densities (Jsc) of 16.01 mA cm−2, and fill factor (FF) of 72.6%. This work not only provides a newly efficient candidate of BDT donor block modified with EDOT conjugated side chains, but also achieves high‐performance large bandgap copolymers for polymer solar cells (PSCs) via the synergistic effect of fluorination and side chain engineering strategies.

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Benzodithiophene-based two-dimensional polymers with extended conjugated thienyltriphenylamine substituents for high-efficiency polymer solar cells

Cited by 16 publications

References 44 publications

Difluorobenzothiadiazole based two-dimensional conjugated polymers with triphenylamine substituted moieties as pendants for bulk heterojunction solar cells

Difluorobenzothiadiazole based two-dimensional conjugated polymers with triphenylamine substituted moieties as pendants for bulk heterojunction solar cells

A New Polythiophene Derivative for High Efficiency Polymer Solar Cells with PCE over 9%

High‐Performance Wide Bandgap Copolymers Using an EDOT Modified Benzodithiophene Donor Block with 10.11% Efficiency

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