X-Shaped donor molecules based on benzo[2,1-b:3,4-b′]dithiophene as organic solar cell materials with PDIs as acceptors

Bibi, Shamsa; Li, Ping; Zhang, Jingping

doi:10.1039/c3ta12421e

Cited by 42 publications

(20 citation statements)

References 60 publications

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“…It is widely reported that PW91PW91 functional yields a better description of transfer integral of organic materials. [39][40][41] So, in our work, we employed PW91PW91/6-31G(d,p) methodology to evaluate the charge transfer integrals after varying the intermolecular distance between two adjacent tetramer segments using potential energy surface scanning (PES). For electronic absorption spectra and vertical singlet electronic transitions, we used time-dependent density functional theory (TD-DFT) using different functionals such as PBE0, B3LYP, CAM-B3LYP.…”

Section: Computational Methodologymentioning

confidence: 99%

Effect of electron‐withdrawing groups on photovoltaic performance of thiophene‐vinyl‐thiophene derivative and benzochalcogenadiazole based copolymers: A computational study

Bhattacharya

Sahoo

Sharma

et al. 2019

Int J of Quantum Chemistry

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We report a density functional theory study of the effect of electron-withdrawing groups such as -F, -CN, -NO 2 on the geometrical, optoelectronic, intramolecular charge transfer (ICT), and photovoltaic properties of (E)-1,2-bis(5-alkyl-[2,3 0bithiophene]-2 0 -yl)ethene (TVT-T) based donor-acceptor (D-A) copolymers with different acceptor units, that is, benzo[c] [1,2,5]thiadiazole, benzo[c][1,2,5]oxadiazole, and benzo[c][1,2,5]selenadiazole. The computed optical absorption spectra of the designed compounds lie in the visible and near-infrared regions. Of all the studied copolymers, -CN substituted and Se-based compound displays the lowest HOMO-LUMO (E H -L ) gap and optical band gap (E opt ). The exciton binding energy (E b ) is found to be smaller for O-incorporated compounds and -CN substituted copolymer as well, inferring more ICT.The electron-hole coherence concentrated over the D-A units is nearly the same for -CN and -NO 2 substituted compounds, but larger in -F derivatives, indicating weak electronhole coupling in the formers. Comparatively larger dipole moment (6.421 Debye-9.829 Debye) and charge transfer length (D CT ) (1.976 Å-3.122 Å) for -CN derivatives lead to enhanced ICT properties. The designed donors yield good hole mobilities (0.127-6.61 cm 2 V −1 s −1 ) and the predicted power conversion efficiencies are calculated to be as high as~6%-7% for -CN and -NO 2 substituted compounds. K E Y W O R D SDFT, donor-acceptor copolymer, electron-withdrawing groups, Intramolecular charge transfer, power conversion efficiency | INTRODUCTIONOrganic solar cells (OSC) or organic photovoltaics (OPVs) incorporating conjugated polymers (CPs) have been a thrust area of research due to their diverse potential applications. In addition, these materials are envisaged to be highly cost-effective, lightweight, mechanically flexible, environmentally benign and hence are considered as efficacious alternatives to the conventional inorganic solar cell. [1][2][3][4][5] The highest achieved power conversion efficiency (PCE) of bulk heterojunction OPV devices containing CPs as donor materials and fullerene derivatives as acceptor units were reported so far to be over 11%. [6][7][8] Conventional organic materials naturally have band gap greater than 2 eV encompassing the only visible range of the solar spectra (300-650 nm). However, to achieve high PCE, materials need to have a lower band gap as well as deeper highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels. A deep HOMO level increases the open circuit voltage

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Section: Computational Methodologymentioning

confidence: 99%

Effect of electron‐withdrawing groups on photovoltaic performance of thiophene‐vinyl‐thiophene derivative and benzochalcogenadiazole based copolymers: A computational study

Bhattacharya

Sahoo

Sharma

et al. 2019

Int J of Quantum Chemistry

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“…In absorption spectra, the drift in increasing value of λ max can be related to the stronger electron withdrawing effect of the acceptor moiety. The energy gap (E g ) of the donor compound decreased by increasing the electron withdrawing strength of the acceptor fragment . Furthermore, excitation energy decreased by increasing the electron withdrawing potential of the acceptor atom.…”

Section: Absorption Spectramentioning

confidence: 99%

“…It presented various improvements e. g. easy purification, definite molecular structure and weight, simplicity and batch‐to‐batch consistency . In present era, many attempts have been made to produce small molecular based solar cells, such as linear geometrical molecules, X shaped donor molecules, star shaped molecules and many other organic based dyes . Remarkable photovoltaic performance has been shown recently by SMOSCs, illustrating their brilliant future in replacing PSCs for global energy demand .…”

Section: Introductionmentioning

confidence: 99%

Theoretical Calculations of the Optical and Electronic Properties of Dithienosilole‐ and Dithiophene‐Based Donor Materials for Organic Solar Cells

et al. 2018

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Six Acceptor‐Donor‐Acceptor (A−D−A) types molecules with dimethyl dithieno[3, 2‐b:2′,3′‐d]silole)−2,6‐diyl (DTS) (M1‐M3) and dimethyl cyclopenta [2, 1‐b;3,4‐b]‐dithiophene (CPDT) (M4‐M6) core flanged by different acceptor units through methylthiophene bridge are evaluated as donor materials for photovoltaic applications. The photovoltaic properties of M1‐M3 and M4‐M6 are compared with standard RaRc and Rb,Rd respectively. Geometry optimization was performed with CAM−B3LYP/6‐31G (d) level of theory. TD‐CAM−B3LYP has been employed for the estimation of excited state properties of the molecules. M1, M2, M3 and M4, M5, M6 symbolized suitable frontier molecular orbital's (FMO's) energy levels with broad absorption spectra. The electron withdrawing substituents impart red shift in absorption spectra along with good consistancy of designed donor molecules. Reorganization energies of donor molecules (M1‐M6) showed ideal properties of charge mobility. M1 and M4 illustrated lowest λe values as compared to λh, thus dictated that designed donor molecules are of good choice for their electron donating ability. Furthermore, M2 and M6 demonstrated shortest Eg of 3.7 and 3.72 eV among HOMO and LUMO energy levels.

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“…The electron mobility increases with the temperature increases, and hole mobility increases with temperature increases at the region of 50-200K, then decreases slightly with increased temperature (200-300K). 32,38 An optimized calculation was performed by using a combination of COMPASS26 force field and Ewald sum methods. The electron transfer ability at room temperature is stronger than the hole transfer ability.…”

Section: Mobilitymentioning

confidence: 99%

Rational design of phenoxazine-based donor–acceptor–donor thermally activated delayed fluorescent molecules with high performance

Zheng

Zhang

2015

Phys. Chem. Chem. Phys.

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A series of donor-acceptor compounds, including asymmetric D-B-Ai-B and symmetric D-B-Ai-B-D topologies, have been designed and investigated using density functional theory and time dependent density functional theory toward highly efficient thermally activated delayed fluorescent (TADF) materials. Phenoxazine (PXZ) is adopted as a donor (D) fragment, while 1,3,4-oxadiazole (A1), benzo[c][1,2,5]thiadiazole (A2), and quinoxaline (A3) are selected as acceptor fragments. A phenyl ring (B) is connected to Ai to extend the π-conjugation, leading to strong electron-withdrawing ability. Our results indicate that the singlet-triplet energy gaps (ΔEST) of symmetric D-B-Ai-B-D compounds are smaller than those of asymmetric D-B-Ai-B ones. For the same topologic series, the ΔEST values decrease with increasing electron-withdrawing strength of B-Ai-B. The lowest ΔEST value has been obtained for D-B-A2-B-D among all these investigated compounds, which displays the most efficient up-conversion from triplet to singlet excited states. Then, the potential energy surface and normal mode analyses were applied to discuss the charge injection and transport characteristics. The designed D-B-Ai-B-D compounds exhibited more effective charge injection with a lower ionization potential and a higher electron affinity than D-B-Ai-B ones. Meanwhile, the temperature dependent mobility was predicted by Marcus theory, both hole and electron mobilities of D-B-Ai-B-D increase with increasing temperature in the range of 5-200 K. However, hole mobility slightly decreases from 200 K to 300 K. The newly designed D-B-A2-B-D compounds demonstrate higher electron and hole mobilities than D-B-A1-B-D, implying that the chemical modification of acceptors effectively improves the carrier transport ability. Our theoretical investigation might provide more chances to challenge the rational design of novel and high-performance TADF-based organic light emitting diodes.

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X-Shaped donor molecules based on benzo[2,1-b:3,4-b′]dithiophene as organic solar cell materials with PDIs as acceptors

Cited by 42 publications

References 60 publications

Effect of electron‐withdrawing groups on photovoltaic performance of thiophene‐vinyl‐thiophene derivative and benzochalcogenadiazole based copolymers: A computational study

Effect of electron‐withdrawing groups on photovoltaic performance of thiophene‐vinyl‐thiophene derivative and benzochalcogenadiazole based copolymers: A computational study

Theoretical Calculations of the Optical and Electronic Properties of Dithienosilole‐ and Dithiophene‐Based Donor Materials for Organic Solar Cells

Rational design of phenoxazine-based donor–acceptor–donor thermally activated delayed fluorescent molecules with high performance

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