Solution-processable oligothiophenes with solubilizing β-alkyl groups for organic photovoltaic cells

Eunhee Lim; Sungkoo Lee; Kyeong K. Lee; In Nam Kang; Sang Jin Moon; Ho Youl Kong; Howard E. Katz

doi:10.1016/j.solmat.2012.07.005

Solution-processable oligothiophenes with solubilizing β-alkyl groups for organic photovoltaic cells

Eunhee Lim, Sungkoo Lee, Kyeong K. Lee, In Nam Kang, Sang Jin Moon, Ho Youl Kong, Howard E. Katz

Department of Applied Chemistry

Research output: Contribution to journal › Article › peer-review

18 Scopus citations

Abstract

Two linear-type π-conjugated small molecules based on thiophene and benzothiadiazole, β-DH5TB(1) and β-DH5TB(2), were synthesized using the Suzuki coupling reaction to have β-substituted solubilizing alkyl groups. The solubility of β-DH5TBs was significantly improved by changing the direction of the alkyl group compared to α-substituted oligothiophene (α-DH5TB). The relationship between the alkyl substitution pattern and the photovoltaic properties was investigated by measuring the optical and electrochemical properties and the film morphology. Among them, the 4-hexyl substituted β-DH5TB(2) showed the lowest optical band gap and HOMO level together with a red-shifted broad UV absorption. In addition, a high degree of molecular alignment was also observed in β-DH5TB(2), indicative of good charge transport. The β-DH5TB(2) film showed higher field-effect mobility (μ _FET) of 6.28×10 ^-4 cm ² V ^-1 s ^-1 than β-DH5TB(1) film. Owing to the improved solubility, two of the synthesized β-DH5TBs could be used as donor materials in solution-processed organic photovoltaic cells (OPVs), whereas the α-DH5TB:PC ₇₁BM blend film showed no photovoltaic properties due to the poor solubility of α-DH5TB. The improved absorption and molecular alignment of the β-DH5TB(2) yielded a device efficiency (0.98%) higher than that of β-DH5TB(1).

Original language	English
Pages (from-to)	165-174
Number of pages	10
Journal	Solar Energy Materials and Solar Cells
Volume	107
DOIs	https://doi.org/10.1016/j.solmat.2012.07.005
State	Published - Dec 2012

Keywords

Benzothiadiazole
Low band gap
Oligothiophene
Organic photovoltaic cells
Solar cells

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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10.1016/j.solmat.2012.07.005

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@article{efed25d9a64b4d83a88242da22dadc43,

title = "Solution-processable oligothiophenes with solubilizing β-alkyl groups for organic photovoltaic cells",

abstract = "Two linear-type π-conjugated small molecules based on thiophene and benzothiadiazole, β-DH5TB(1) and β-DH5TB(2), were synthesized using the Suzuki coupling reaction to have β-substituted solubilizing alkyl groups. The solubility of β-DH5TBs was significantly improved by changing the direction of the alkyl group compared to α-substituted oligothiophene (α-DH5TB). The relationship between the alkyl substitution pattern and the photovoltaic properties was investigated by measuring the optical and electrochemical properties and the film morphology. Among them, the 4-hexyl substituted β-DH5TB(2) showed the lowest optical band gap and HOMO level together with a red-shifted broad UV absorption. In addition, a high degree of molecular alignment was also observed in β-DH5TB(2), indicative of good charge transport. The β-DH5TB(2) film showed higher field-effect mobility (μ FET) of 6.28×10 -4 cm 2 V -1 s -1 than β-DH5TB(1) film. Owing to the improved solubility, two of the synthesized β-DH5TBs could be used as donor materials in solution-processed organic photovoltaic cells (OPVs), whereas the α-DH5TB:PC 71BM blend film showed no photovoltaic properties due to the poor solubility of α-DH5TB. The improved absorption and molecular alignment of the β-DH5TB(2) yielded a device efficiency (0.98%) higher than that of β-DH5TB(1).",

keywords = "Benzothiadiazole, Low band gap, Oligothiophene, Organic photovoltaic cells, Solar cells",

author = "Eunhee Lim and Sungkoo Lee and Lee, {Kyeong K.} and Kang, {In Nam} and Moon, {Sang Jin} and Kong, {Ho Youl} and Katz, {Howard E.}",

year = "2012",

month = dec,

doi = "10.1016/j.solmat.2012.07.005",

language = "English",

volume = "107",

pages = "165--174",

journal = "Solar Energy Materials and Solar Cells",

issn = "0927-0248",

publisher = "Elsevier B.V.",

}

TY - JOUR

T1 - Solution-processable oligothiophenes with solubilizing β-alkyl groups for organic photovoltaic cells

AU - Lim, Eunhee

AU - Lee, Sungkoo

AU - Lee, Kyeong K.

AU - Kang, In Nam

AU - Moon, Sang Jin

AU - Kong, Ho Youl

AU - Katz, Howard E.

PY - 2012/12

Y1 - 2012/12

N2 - Two linear-type π-conjugated small molecules based on thiophene and benzothiadiazole, β-DH5TB(1) and β-DH5TB(2), were synthesized using the Suzuki coupling reaction to have β-substituted solubilizing alkyl groups. The solubility of β-DH5TBs was significantly improved by changing the direction of the alkyl group compared to α-substituted oligothiophene (α-DH5TB). The relationship between the alkyl substitution pattern and the photovoltaic properties was investigated by measuring the optical and electrochemical properties and the film morphology. Among them, the 4-hexyl substituted β-DH5TB(2) showed the lowest optical band gap and HOMO level together with a red-shifted broad UV absorption. In addition, a high degree of molecular alignment was also observed in β-DH5TB(2), indicative of good charge transport. The β-DH5TB(2) film showed higher field-effect mobility (μ FET) of 6.28×10 -4 cm 2 V -1 s -1 than β-DH5TB(1) film. Owing to the improved solubility, two of the synthesized β-DH5TBs could be used as donor materials in solution-processed organic photovoltaic cells (OPVs), whereas the α-DH5TB:PC 71BM blend film showed no photovoltaic properties due to the poor solubility of α-DH5TB. The improved absorption and molecular alignment of the β-DH5TB(2) yielded a device efficiency (0.98%) higher than that of β-DH5TB(1).

AB - Two linear-type π-conjugated small molecules based on thiophene and benzothiadiazole, β-DH5TB(1) and β-DH5TB(2), were synthesized using the Suzuki coupling reaction to have β-substituted solubilizing alkyl groups. The solubility of β-DH5TBs was significantly improved by changing the direction of the alkyl group compared to α-substituted oligothiophene (α-DH5TB). The relationship between the alkyl substitution pattern and the photovoltaic properties was investigated by measuring the optical and electrochemical properties and the film morphology. Among them, the 4-hexyl substituted β-DH5TB(2) showed the lowest optical band gap and HOMO level together with a red-shifted broad UV absorption. In addition, a high degree of molecular alignment was also observed in β-DH5TB(2), indicative of good charge transport. The β-DH5TB(2) film showed higher field-effect mobility (μ FET) of 6.28×10 -4 cm 2 V -1 s -1 than β-DH5TB(1) film. Owing to the improved solubility, two of the synthesized β-DH5TBs could be used as donor materials in solution-processed organic photovoltaic cells (OPVs), whereas the α-DH5TB:PC 71BM blend film showed no photovoltaic properties due to the poor solubility of α-DH5TB. The improved absorption and molecular alignment of the β-DH5TB(2) yielded a device efficiency (0.98%) higher than that of β-DH5TB(1).

KW - Benzothiadiazole

KW - Low band gap

KW - Oligothiophene

KW - Organic photovoltaic cells

KW - Solar cells

UR - http://www.scopus.com/inward/record.url?scp=84865989716&partnerID=8YFLogxK

U2 - 10.1016/j.solmat.2012.07.005

DO - 10.1016/j.solmat.2012.07.005

M3 - Article

AN - SCOPUS:84865989716

SN - 0927-0248

VL - 107

SP - 165

EP - 174

JO - Solar Energy Materials and Solar Cells

JF - Solar Energy Materials and Solar Cells

ER -

Solution-processable oligothiophenes with solubilizing β-alkyl groups for organic photovoltaic cells

Abstract

Keywords

UN SDGs

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