- Acene Ring Size Optimization in Fused Lactam Polymers Enabling High n-Type Organic Thermoelectric Performance
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Three n-type fused lactam semiconducting polymers were synthesized for thermoelectric and transistor applications via a cheap, highly atom-efficient, and nontoxic transition-metal free aldol polycondensation. Energy level analysis of the three polymers demonstrated that reducing the central acene core size from two anthracenes (A-A), to mixed naphthalene-anthracene (A-N), and two naphthalene cores (N-N) resulted in progressively larger electron affinities, thereby suggesting an increasingly more favorable and efficient solution doping process when employing 4-(2,3-dihydro-1,3-dimethyl-1H-benzimidazol-2-yl)-N,N-dimethylbenzenamine (N-DMBI) as the dopant. Meanwhile, organic field effect transistor (OFET) mobility data showed the N-N and A-N polymers to feature the highest charge carrier mobilities, further highlighting the benefits of aryl core contraction to the electronic performance of the materials. Ultimately, the combination of these two factors resulted in N-N, A-N, and A-A to display power factors (PFs) of 3.2 μW m-1 K-2, 1.6 μW m-1 K-2, and 0.3 μW m-1 K-2, respectively, when doped with N-DMBI, whereby the PFs recorded for N-N and A-N are among the highest reported in the literature for n-type polymers. Importantly, the results reported in this study highlight that modulating the size of the central acene ring is a highly effective molecular design strategy to optimize the thermoelectric performance of conjugated polymers, thus also providing new insights into the molecular design guidelines for the next generation of high-performance n-type materials for thermoelectric applications.
- Chen, Hu,Moser, Maximilian,Wang, Suhao,Jellett, Cameron,Thorley, Karl,Harrison, George T.,Jiao, Xuechen,Xiao, Mingfei,Purushothaman, Balaji,Alsufyani, Maryam,Bristow, Helen,De Wolf, Stefaan,Gasparini, Nicola,Wadsworth, Andrew,McNeill, Christopher R.,Sirringhaus, Henning,Fabiano, Simone,McCulloch, Iain
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supporting information
p. 260 - 268
(2021/01/13)
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- Excited-state intermolecular proton transfer dependent on the substitution pattern of anthracene-diurea compounds involved in fluorescent ON1-OFF-ON2 response by the addition of acetate ions
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We report anthracene-diurea compounds which behave as anion sensors based on the fluorescence emission regulated by the substitution position on the anthracene ring. Anthracene-diurea compounds exhibit different excited-state intermolecular proton transfer (ESIPT) reactions depending on the pattern of the substituents. Three new anthracene-diurea compounds that have two phenylurea groups substituted at different positions on anthracene were synthesized. These compounds formed complexes with acetate ions through intermolecular hydrogen bonding between N-H and CO moieties in the ground state. The positions of the substituents greatly affected the excited-state intermolecular proton transfer. 1,5BPUA with urea groups at the 1 and 5 positions exhibited ESIPT reaction, which is energetically favorable for tautomer formation, in the presence of TBAAc. In contrast, 2,6BPUA with urea groups at low-electron-density positions (2 and 6 positions) showed no ESIPT reaction due to the inversion of the lowest unoccupied molecular orbital (LUMO) energy levels of the normal and tautomer states. Detailed spectroscopic measurements showed that the LUMO energy level of the normal form was lowered because the urea group acted as an electron-withdrawing group. In addition, 9,10BPUA exhibited strong electronic interactions between the two phenylurea moieties at the 9 and 10 positions, resulting in an ON1-OFF-ON2 response for acetate ions. Our findings offer guidelines for the molecular design of materials with anthracene moieties based on the substitution patterns of anthracene derivatives.
- Matsumoto, Hisato,Nishimura, Yoshinobu,Arai, Tatsuo
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p. 6575 - 6583
(2017/08/16)
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- Coupled π-conjugated chromophores: Squaraine dye dimers as two connected pendulums
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Intense absorption ability in the near infrared (NIR) region is mandatory for many technologies and applications. The design thereof is however quite complex since only a few dye classes show these properties. Polymeric squaraine dyes have them however they are mostly hardly soluble. Herein four dimeric soluble and easy to prepare squaraine dye dimers are reported with absorption maxima between 679 and 805 nm. The synthesis, characterisation, the determination of the physicochemical properties and the in silico study of the calculated molecular geometry, the molecular orbitals, and the calculated total charge density surface were compared. The coupling of the two chromophores is concluded as a matter of the distance in-between, the π-electron system of the bridge, the spatial orientation thereof, and the spatial orientation of the electronic transition moment. The closer the two chromophores were and the less out-of-plane elements the bridge has, the smaller the optical band gap is.
- Kuster, Simon,Geiger, Thomas
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p. 110 - 116
(2014/11/07)
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- Intramolecular behaviors of anthryldicarbenic systems: Dibenzo[b,f]pentalene and, 1H,5H-dicyclobuta[de,kl]anthracene
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9,10-Bis[methoxy(trimethylsilyl)methyl]anthracenes (24), synthesized from 9,10-dilithioanthracene (26) and bromomethoxytrimethylsilylmethane (27, 2 equiv), decompose (550-650 °C/10-3 mmHg) carbenically to dibenzo[b,f]pentalene (28, >48%). 9,10-Anthryldicarbenes 39 or their equivalents convert to pentalene 28 rather than di-peri-cyclobutanthracenes 30 and 31, benzobiphenylene 32, or extended rearrangement products 33-38. Formation of 28 from 24 raises questions with respect to the behavior of 1,3,4,6-cycloheptatetraenyl-1-carbenes 49, 2,4,5,7-cyclooctatetraenylidene 51, 2,5,7-cyclooctatriene-1,4-diylidene 52, 1,2,4,5,7-cyclooctapentaene 53, and bicyclo[4.1.0]heptatrienyl-1-carbenes 54 and to carbon-skeleton and hydrogen rearrangements of anthryldicarbenes 39 and/or their equivalents at various temperatures. 1,5-Bis[methoxy(trimethylsilyl)methyl]anthracenes (25), prepared from 1,5-diiodoanthracene (63) and methoxytrimethylsilylmethylzinc bromide (57, 2 equiv) as catalyzed by PdCl2(PPh3)2, yield the di-peri-carbenic reaction product 1H,5H-dicyclobuta[de,kl]anthracene (30, >40%) on pyrolysis at 550-650 °C/10-3 mmHg. Proof of structure and various aspects of the mechanisms of formation of 30 are discussed.
- Kendall,Shechter
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p. 6643 - 6649
(2007/10/03)
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