N-Alkylthienopyrroledione versus benzothiadiazole pulling units in push–pull copolymers used for photovoltaic applications: density functional theory study

2016 ◽  
Vol 18 (2) ◽  
pp. 1017-1024 ◽  
Author(s):  
Jamin Ku ◽  
Yeongrok Gim ◽  
Yves Lansac ◽  
Yun Hee Jang
Keyword(s):  
Density Functional Theory ◽  
Solar Cells ◽  
Band Gap ◽  
Organic Solar Cells ◽  
Density Functional ◽  
Bulk Heterojunction ◽  
Density Functional Theory Study ◽  
Functional Theory ◽  
Low Band Gap ◽  
Photovoltaic Applications

Low-band-gap push–pull copolymers are promising donor materials for bulk heterojunction organic solar cells.

scholarly journals Designing small organic non-fullerene acceptor molecules with diflorobenzene or quinoline core and dithiophene donor moiety through density functional theory

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ghulam Bary ◽  
Lubna Ghani ◽  
Muhammad Imran Jamil ◽  
Muhammad Arslan ◽  
Waqar Ahmed ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Solar Cells ◽  
Band Gap ◽  
Gas Phase ◽  
Organic Solar Cells ◽  
Density Functional ◽  
Excitation Energies ◽  
Functional Theory ◽  
Reorganization Energies ◽  
Donor Moiety

AbstractThe non-fullerene acceptors A1–A5 with diflourobenzene or quinoline core (bridge) unit, donor cyclopenta[1,2-b:3,4-b′]dithiophene unit and 2-(2-methylene-3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile as acceptor unit with additional phenyl, fulvene or thieno[3,2-d]pyrimidinyl 5-oxide groups have been designed through DFT calculations. The optimization of molecular geometries were performed with density functional theory (DFT) at B3LYP 6-31G (d,p) level of theory. The frontier molecular orbital (FMO) energies, band gap energies and dipole moments (ground and excited state) have been calculated to probe the photovoltaic properties. The band gap (1.42–2.01 eV) and dipole moment values (5.5–18. Debye) showed that these designed acceptors are good candidates for organic solar cells. Time-Dependent Density Functional Theory (TD-DFT) results showed λmax (wave length at maximum absorption) value (611–837 nm), oscillator strength (f) and excitation energies (1.50–2.02 eV) in gas phase and in CHCl3 solvent (1.48–1.89 eV) using integral equation formalism variant (IEFPCM) model. The λmax in CHCl3 showed marginal red shift for all designed acceptors compared with gas phase absorption. The partial density of states (PDOS) has been plotted by using multiwfn which showed that all the designed molecules have more electronic distribution at the donor moiety and lowest at the central bridge. The reorganization energies of electron (λe) (0.0007 eV to 0.017 eV), and the hole reorganization energy values (0.0003 eV to − 0.0403 eV) were smaller which suggested that higher charged motilities. The blends of acceptors A1–A5 with donor polymer D1 provided open circuit voltage (Voc) and ∆HOMO off-set of the HOMO of donor and acceptors. These blends showed 1.04 to 1.5 eV values of Voc and 0 to 0.38 eV ∆HOMO off set values of the donor–acceptor bends which indicate improved performance of the cell. Finally, the blend of D1–A4 was used for the study of distribution of HOMO and LUMO. The HOMO were found distributed on the donor polymer (D1) while the A4 acceptor was found with LUMO distribution. Based on λmax values, and band gap energies (Eg), excitation energies (Ex), reorganization energies; the A3 and A4 will prove good acceptor molecules for the development of organic solar cells.

Density Functional Theory Study on Energy Band Gap of Armchair Silicene Nanoribbons with Periodic Nanoholes

MRS Advances ◽  
2016 ◽  
Vol 1 (22) ◽  
pp. 1613-1618 ◽  
Author(s):  
Sadegh Mehdi Aghaei ◽  
Irene Calizo
Keyword(s):  
Density Functional Theory ◽  
Band Gap ◽  
Energy Band ◽  
Quantum Confinement ◽  
Density Functional ◽  
Quantum Confinement Effect ◽  
Density Functional Theory Study ◽  
Energy Band Gap ◽  
Functional Theory ◽  
Silicene Nanoribbons

ABSTRACTIn this study, density functional theory (DFT) is employed to investigate the electronic properties of armchair silicene nanoribbons perforated with periodic nanoholes (ASiNRPNHs). The dangling bonds of armchair silicene nanoribbons (ASiNR) are passivated by mono- (:H) or di-hydrogen (:2H) atoms. Our results show that the ASiNRs can be categorized into three groups based on their width: W = 3P − 1, 3P, and 3P + 1, P is an integer. The band gap value order changes from “EG (3P − 1) < EG (3P) < EG (3P + 1)” to “EG (3P + 1) < EG (3P − 1) < EG (3P)” when edge hydrogenation varies from mono- to di-hydrogenated. The energy band gap values for ASiNRPNHs depend on the nanoribbons width and the repeat periodicity of the nanoholes. The band gap value of ASiNRPNHs is larger than that of pristine ASiNRs when repeat periodicity is even, while it is smaller than that of pristine ASiNRs when repeat periodicity is odd. In general, the value of energy band gap for ASiNRPNHs:2H is larger than that of ASiNRPNHs:H. So a band gap as large as 0.92 eV is achievable with ASiNRPNHs of width 12 and repeat periodicity of 2. Furthermore, creating periodic nanoholes near the edge of the nanoribbons cause a larger band gap due to a strong quantum confinement effect.

Design of low band gap small molecules with alkyldicyanovinyl acceptor and different donor groups for efficient bulk heterojunction organic solar cells

2015 ◽  
Author(s):  
Yuriy N. Luponosov ◽  
Jie Min ◽  
Alexander N. Solodukhin ◽  
Sergei N. Chvalun ◽  
Tayebeh Ameri ◽  
...  
Keyword(s):  
Solar Cells ◽  
Small Molecules ◽  
Band Gap ◽  
Organic Solar Cells ◽  
Bulk Heterojunction ◽  
Low Band Gap
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