Molecular Design of Benzothiadiazole Derivatives Electron Acceptors and Matching of Donor-Acceptor Materials

作者：Shao Rong; Yang Xinbo; Yin Shiwei; Wang Wenliang^*

来源：Acta Chimica Sinica, 2016, 74(8): 676-682.

DOI：10.6023/A16050268

• benzothiadiazole derivatives
• electronic acceptors
• Donor-Acceptor interface
• electronic coupling
• the power conversion efficiency

To better understand the relationships between the microstructure and the optoelectronic characteristics of the electron acceptor and to meet the needs of donor-acceptor materials with excellent optical properties for solar cell, a series of acceptor molecules with A'-pi-A-pi-A' type are designed. In these molecules, the core framework of benzothiadiazole is used as an acceptor (A), three kinds of conjugated heterocyclics (A') with different abilities of electron-withdrawing and steric effects are applied as the terminals, and various conjugated structures, such as the double bond, thiophene, benzothiophene and vinyl thiophene, are utilized as pi-bridge, respectively. Their geometric configurations, the characteristics of frontier molecular orbital, optical properties, as well as the electronic reorganization energy are predicted by DFT-B3LYP and TD-DFT-CAM-B3LYP. Solvent effects from acetone and chlorobenzene on molecular properties are studied. Furthermore, the Donor-Acceptor (D-A) interfaces are respectively constructed by combining the excellent acceptors with the selected two donors. The DFT-D3 method is used to scan the binding energy of D-A complex, in order to determine the stacked displacement of the interface. The degree of interface recombination is evaluated by calculating electronic coupling (V-if) between HOMO of donors and LUMO of acceptors. The results show that modifying benzothiadiazole with a reasonable substituent is an effective way to adjust LUMO energy levels and lead to the noticeable variation of the energy gap. Combining planar electron acceptor materials (A'-pi-A-pi-A' type) with non-planar electron donor materials (D), to form the optical active layer is a practical approach for preventing interface recombination and achieving high open-circuit voltage (V-oc). Considering Delta E-L, Vif, light absorption efficiency, and solvation effect, D1-1a gamma and D1-2a gamma combinations are the most promising candidates of optical active layer materials in organic solar cell.

• 出版日期2016
• 单位陕西师范大学