Synthesis and properties of low band gap polymers based on thienyl thienoindole as a new electron-rich unit for organic photovoltaics

Shim, Joo Young; Baek, Ji-Yeon; Kim, Juae; Park, Song Yi; Kim, Jin-Woo; Kim, Il; Chun, Ho Hwan; Kim, Jin Young; Suh, Hongsuk

doi:10.1039/c5py00501a

Cited by 16 publications

(2 citation statements)

References 41 publications

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“…Similarly, bromine‐containing compound 5b is more planar than reference compound 5a because of p‐π conjugation. In general, if π electron delocalization was enhanced, the E g value would be reduced . It would further result in that the λ max values would be redshifted.…”

Section: Resultsmentioning

confidence: 99%

Effect of bromine substituent on optical properties of aryl compounds

Zhang

Yang

et al. 2016

J of Physical Organic Chem

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Substituents significantly affect optical properties of organic compounds. In this study, a series of organic compounds were synthesized. Ultraviolet‐visible and cyclic voltammetry spectra were determined. The relationships between the number of π electron in an aryl ring and the redshift (and molecular orbital energy levels) were studied. To investigate mechanisms of the bromine substituent effects, theoretical calculations were carried out. Ultraviolet‐visible spectra of bromine‐containing compounds exhibit obvious redshifts (0.04‐0.17 eV) of the maximal absorption wavelengths and enhanced absorbance (11%‐57%) compared with corresponding reference compounds. The lowest unoccupied and highest occupied molecular orbital energy levels of compounds containing bromine substituents are 0.05 to 0.60 and 0.02 to 0.40 eV lower than that of corresponding reference compounds. On the whole, the redshifts and the reduced molecular orbital energy levels caused by bromine substituent decrease with the increase in the number of π electron in an aryl ring. The effects would be attributed to strong p‐π conjugation between p electron in the bromine substituent and π electrons in aryl rings. Therefore, this paper suggests a useful way for tuning optical absorption and molecular orbital energy levels of aryl compounds.

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Section: Resultsmentioning

confidence: 99%

Effect of bromine substituent on optical properties of aryl compounds

Zhang

Yang

et al. 2016

J of Physical Organic Chem

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“…In particular, we used the aforementioned electron‐rich unit, 2‐TTI, which has a structure of indole fused with thiophene as a structural isomer of 6‐(2‐thienyl)‐4H‐thieno[3,2‐ b ]indole (3‐TTI), and coupled it with four types of BT–MBI derivatives. In the 2‐TTI unit, the six‐membered benzene ring in the carbazole unit was replaced with the five‐membered thiophene ring to reduce the steric hindrance and improve the planarity of the conjugated backbone, ICT effect, and electron‐donating ability.…”

Section: Introductionmentioning

confidence: 99%

Syntheses and optical, electrochemical, and photovoltaic properties of polymers with 6‐(2‐thienyl)‐4H‐thieno[2,3‐b]indole with a variety of electron‐deficient units

Kim

Chae

et al. 2019

J of Applied Polymer Sci

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Conjugated polymers were synthesized and used for polymer solar cells with new electron-rich units, 6-(2-thienyl)-4H-thieno [2,3-b]indole (2-TTI). 2-TTI was coupled with electron-pulling units, including benzothiadiazole and benzimidazole derivatives, to provide push-pull types of conjugated polymers (poly(8-(heptadecan-9-yl)-6-(thiophen-, and poly(8-(heptadecan-9-yl)-6-(thiophen-2-yl)-8H-thieno[2,3-b]indole)-alt-(2,2-dimethyl-5,6-bis(octyloxy)-4,7-di(thiophen-2-yl)-2H-benzimidazole) (PTTIDOMBI)). The synthesized conjugated polymers provided deep highest occupied molecular orbital energy levels for higher open-circuit voltages (V OC ). The device composed of PTTIDOMBI and [6,6]-Phenyl C 71 butyric acid methyl ester PC 71 BM (1:2) with chloronaphthalene additive showed a V OC of 0.72 V, a short-circuit current (J SC ) of 9.16 mA/cm 2 , and a fill factor of 0.43; this gave a power conversion efficiency (PCE) of 2.84%. The PTTIDOMBI provided better morphology for enhanced charge transport, and this led to the higher J SC and PCE of the organic solar cells.

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Syntheses and Properties of Conjugated Polymers Containing Thieno[2,3‐b]indole with Different Electron‐deficient Units

Kim

Chae

et al. 2019

Bulletin Korean Chem Soc

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New conjugated polymers using electron‐rich unit, thieno[2,3‐b]indole (2‐TI), and various electron‐deficient units were synthesized for the utilization in the photovoltaics. The synthesized polymers (PTIBTI, PTITPD, and PTIID) with various types of electron‐deficient units showed different electronic structure and properties. The PTITPD provides the higher VOC through suitable energy level offset of LUMO (donor)‐LUMO (PC71BM) and improved JSC resulting from better crystallinity, charge carrier mobility and morphology, leading to the higher PCE value of OPV out of the series. This result illustrates that the combination of various electron‐deficient units affects the electronic structure, such as the HOMO/LUMO energy levels and bandgap in addition to the morphology and the carrier mobility, implying that variation of the electron‐deficient unit should be explored for the utilization of a given electron‐rich unit to produce the better performance of the device.

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Synthesis and properties of low band gap polymers based on thienyl thienoindole as a new electron-rich unit for organic photovoltaics

Cited by 16 publications

References 41 publications

Effect of bromine substituent on optical properties of aryl compounds

Effect of bromine substituent on optical properties of aryl compounds

Syntheses and optical, electrochemical, and photovoltaic properties of polymers with 6‐(2‐thienyl)‐4H‐thieno[2,3‐b]indole with a variety of electron‐deficient units

Syntheses and Properties of Conjugated Polymers Containing Thieno[2,3‐b]indole with Different Electron‐deficient Units

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