Electronic and photophysical properties of the bend D–T–A–T–D derivatives for small-molecule organic photovoltaic (SM-OPV) solar cells: a DFT and TD-DFT investigation

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• 作者：Chin-Kuen Tai ; Chun-An Hsieh ; Ken-Hao Chang…
• 刊名：Research on Chemical Intermediates
• 出版年：2016
• 出版时间：September 2016
• 年：2016
• 卷：42
• 期：9
• 页码：6907-6927
• 全文大小：1,226 KB
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Chemistry
  Catalysis
  Physical Chemistry
  Inorganic Chemistry
  
• 出版者：Springer Netherlands
• ISSN：1568-5675
• 卷排序：42

文摘

A series of D–T–A–T–D derivatives (D, electron-donating moiety; T, π-conjugated linker; A, electron-acceptor moiety) with seven electron donor moieties and various electron abilities are designed to investigate the influence of the donor on photophysical properties for small-molecule organic photovoltaic solar cells. The 4,8-dimethoxybenzodithiophene (D₁), triphenyldsramine (D₂), 4-methoxy-N-(4-methoxyphenyl)-N-phenylaniline (D₃), 9,9-dimethyl-9H-fluorene (D₄), 9-methyl-9H-carbazole (D₅), 4-methyl-4H-dithieno-pyrrole (D₆), and 4,4-dimethyl-4H-cyclopenta-dithiophene (D₇) are adopted as the electron donor moiety. The BDTC (buta-1,3-diene-1,1,4,4-tetracarbonitrile) is used for the A moiety, and the thiophene (T) is used for the π-conjugated linker. The optimized structure of D–T–A–T–D derivatives exhibits the bend molecular conformation due to the steric effect within the A moiety. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies of these derivatives are dependent on the electron donating ability of D, which influences the open-circuit voltage and driving force. Reorganization energy suggests that these derivatives are good hole-transporting type materials. Projected density of state analysis demonstrates that in the HOMO, the electron density distribution is delocalized on the terminal D and T moieties, while in the LUMO, the electron density distribution is localized mainly on the A moiety. The maximum absorption peak, which has relatively high light harvesting efficiency, is due to the π to π* transition and can be tuned by the electron-donating ability and the resonance energy of the D moiety. The bend D₆–T–A–T–D₆/D₇–T–A–T–D₇ derivatives with D moiety of 4-methyl-4H-dithieno-pyrrole (D₆) and 4,4-dimethyl-4H-cyclopenta-dithiophene (D₇) are good candidates as electron donor materials for SM-OPV.KeywordsOptical materialsAb initio calculationsElectronic structureOptical properties