Improved open-circuit voltage of benzodithiophene based polymer solar cells using bulky terthiophene side group

The effect of the presence of hexyl group in thiophene on the photophysical and electrochemical properties of poly[(9,9-dioctyluorene)22,7-diyl-alt-(4,7-bis(3-hexylthien-5-yl)22,1,3-benzothiadiazole)22The copolymers present electron donor-acceptor architecture and are synthesized by Suzuki coupling reaction. The UV/Vis spectra show absorption maximum in the wavelength range of blue and orange, which are associated with different segments of the polymer backbone. Addition of hexyl substituent groups has a positive effect on the molar absorptivity and increases the emission and absorption intensities due to fluorene and thiophene-benzothiadiazole-thiophene (TBT) units, although an increment in the bandgap is observed. Cyclic voltammetry study of the polymer films reveal irreversible reduction and oxidation processes of the TBT units in the polymer chain and the HOMO and LUMO energy levels suggest ambipolar character for the polymers, while the electrochemical bandgaps are consistent with the absorbance measurements.

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“…The optical bandgap (

E_{g}^{o p t}

) was estimated from

λ_{o n s e t}

(the longest wavelength absorbed by the sample) in the UV‐Vis spectrum, as follows:

E_{g}^{o p t} = \frac{1240}{λ_{o n s e t}}

…”

Section: Methodsmentioning

confidence: 99%

Effect of hexyl substituent groups on photophysical and electrochemical properties of the poly[(9,9‐Dioctyluorene)−2,7‐diyl‐alt‐(4,7‐bis (3‐Hexylthien‐5‐Yl)−2,1,3‐Benzothiadiazole)−2′,2″‐diyl]

Silva

Takimoto

Santos

et al. 2016

J Polym Sci B Polym Phys

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“…The use of donor polymers containing conjugated side chains, known as two‐dimensional (2D) conjugated polymers, is expected to improve the performances of OPVs because their extended conjugated side groups broaden the absorption spectra range in the visible region and increase the molar extinction coefficient, which can enhance the J SC values of PSCs. BDT‐based polymers that incorporate various conjugated side chains have been widely studied and have contributed to highly efficient OPV applications . Recently, Tajima and coworkers reported the synthesis and characterization of a conjugated tris(thienylenevinylene) (TTV) group that incorporated BDT‐based conjugated terpolymers .…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of highly conjugated side‐group‐substituted benzo[1,2‐b:4,5‐b′]dithiophene‐based copolymer for use in organic solar cells

Kim

Park

Lee

et al. 2017

J. Polym. Sci. Part A: Polym. Chem.

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A new donor-acceptor (D-A) conjugated copolymer based on benzo [1,2-b:4,5-b 0 ]dithiophene (BDT) and thieno [3,4c]pyrrole-4,6-dione (TPD) was synthesized via a Stille crosscoupling reaction. A highly conjugated thiophene-based side group, tris(thienylenevinylene) (TTV), was incorporated into each BDT unit to generate the two-dimensional D-A copolymer (PBDT-TTV). An alkoxy-substituted BDT-based TPD copolymer (PBDT-OR) was synthesized using the same polymerization method for comparison. PBDT-TTV thin films produced two distinct absorption peaks. The shorter wavelength absorption (458 nm) was attributed to the BDT units containing the TTV group, and the longer wavelength band (567-616 nm) was attributed to intramolecular charge transfer between the BDT donor and the TPD acceptor. The highest occupied molecular orbital energy levels of PBDT-OR and PBDT-TTV were V C 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 653-660

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“…Then the alkylthienyl‐substituted BDT immediately attracted much attention of many researchers. Nowadays, many important progresses of PCEs were associated with the BDT‐based 2D polymers, and currently the BDT‐based 2D polymers have become one of the major families of polymeric photovoltaic materials . For example, very recently single‐junction PSCs based on 2D‐conjugated polymer (PTB7‐Th) showed a PCE exceeding 10% by a new device structure …”

Section: Introductionmentioning

confidence: 99%

Synthesis and Optoelectronic Properties of Benzo[1,2‐b:4,5‐b′]dithiophene‐Based Copolymers with Conjugated 2‐(2‐Ethylhexyl)‐3,4‐dimethoxythiophene Side Chains

Wang

Chen

Guo

et al. 2016

Macro Chemistry & Physics

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In order to regulate the electronic ability of benzo [1,2-b:4,5-b′]dithiophene (BDT), the new electron-donating unit (BDTOT) is designed and synthesized which consists of a BDT backbone with conjugated 2-(2-ethylhexyl)-3,4-dimethoxythiophene side chains. By alternating copolymerization of BDTOT with electron-accepting units of fluorinated benzothiadiazole (FBT), benzothiadiazole (BT), and pyrrolo[3,4-c]pyrrole-1,4-dione (DPP), three donor-acceptor (D-A) copolymers (PBDTOT-FBT, PBDTOT-BT, and PBDTOT-DPP) have been developed for PSC applications. The impact of dimethoxythiophene substituent and the electron-accepting strength of the acceptor units on the absorption, HOMO/LUMO energy levels, and photovoltaic properties of the resultant polymers is investigated in detail. PBDTOT-BT and PBDTOT-DPP exhibit relatively narrower bandgaps and PBDTOT-FBT possesses a down-shifted HOMO energy level as compared to their corresponding analogs without methoxy groups onto the conjugated thiophene side chains. The screening of the different blend ratio, the processing additive, and polar solvent post-treatment is conducted to optimize the polymer solar cell (PSC) devices. PSCs with PBDTOT-FBT as donor deliver a power conversion efficiency (PCE) of 2.55%. By treatment of the active layer with methanol to tailor the morphology, the solar cell based on PBDTOT-FBT exhibits the remarkably improved PCE of 4.84% with a V oc of 0.92 V, a J sc of 8.71 mA cm −2 , and an FF of 60.3%.

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Improved open-circuit voltage of benzodithiophene based polymer solar cells using bulky terthiophene side group

Cited by 23 publications

References 53 publications

Effect of hexyl substituent groups on photophysical and electrochemical properties of the poly[(9,9‐Dioctyluorene)−2,7‐diyl‐alt‐(4,7‐bis (3‐Hexylthien‐5‐Yl)−2,1,3‐Benzothiadiazole)−2′,2″‐diyl]

Effect of hexyl substituent groups on photophysical and electrochemical properties of the poly[(9,9‐Dioctyluorene)−2,7‐diyl‐alt‐(4,7‐bis (3‐Hexylthien‐5‐Yl)−2,1,3‐Benzothiadiazole)−2′,2″‐diyl]

Synthesis and characterization of highly conjugated side‐group‐substituted benzo[1,2‐b:4,5‐b′]dithiophene‐based copolymer for use in organic solar cells

Synthesis and Optoelectronic Properties of Benzo[1,2‐b:4,5‐b′]dithiophene‐Based Copolymers with Conjugated 2‐(2‐Ethylhexyl)‐3,4‐dimethoxythiophene Side Chains

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