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以染料分子D5为原型,采用不同类型和数量的共轭桥单元来设计D-π-A型有机分子,采用密度泛函理论(DFT)和含时密度泛函理论(TDDFT)来模拟计算分子的形貌、分子轨道能级以及紫外-可见光谱,为染料敏化太阳能电池(DSSCs)的敏化分子寻找适合的共轭桥.采用“次甲基链”、“呋喃环”或“噻吩环”、“次甲基链和呋喃环”或“次甲基链和噻吩环”作为共轭桥单元,使得分子的吸收光谱依次红移.随着共轭桥单元的增加,分子的吸收光谱有剧烈的红移,但随着共轭桥单元数量的进一步增加,分子吸收光谱的红移现象减弱.分子的最低未占据分子轨道(LUMO)能级逐渐降低,而最高占据分子轨道(HOMO)能级逐渐升高.采用3个“次甲基链和呋喃环”或者“次甲基链和噻吩环”作为共轭桥时,HOMO能级已经高于氧化还原电解质的能级,而在极性溶液中,由2个“次甲基链和噻吩环”单元作为有机分子的共轭桥时,分子的HOMO能级已经高于氧化还原电解质的能级了.采用“次甲基链和呋喃环”或“次甲基链和噻吩环”单元作为有机分子的共轭桥时,吸收光谱有明显的红移,但对于DSSCs的敏化分子,这样的共轭桥单元只能有1-2个,不宜过多.
The dye molecule D5 was used as a prototype to design D-π-A type organic molecules by using different types and numbers of conjugated bridging units. Density functional theory (DFT) and time-dependent density functional theory (TDDFT) The molecular orbital energy level and the UV-Vis spectrum of the dye-sensitized solar cells (DSSCs) Or “thiophene ring ”, “methine chain and furan ring ” or “methine chain and thiophene ring ” as a conjugate bridging unit, so that the molecular absorption spectra in turn red shift with conjugation However, with the increase of the number of conjugated bridging units, the red shift phenomenon of molecular absorption spectra is weakened, and the lowest unoccupied molecular orbital (LUMO) level of the molecule gradually decreases , While the highest occupied molecular orbital (HOMO) energy level is gradually increased.When 3 “methine chains and furan ring” or “methine chain and thiophene ring” are used as the conjugate bridge, the HOMO energy level Is already above the energy level of the redox electrolyte and in the polar solution it is composed of 2 “methine chains and thiophene rings” as organic molecules When the yoke is bridged, the HOMO energy level of the molecule is already above the energy level of the redox electrolyte, using a “methine chain and furan ring” or a “methine chain and a thiophene ring” unit as the organic molecule Yoke bridge, the absorption spectrum of significant redshift, but for DSSCs sensitized molecules, such a conjugate bridge unit can only have 1-2, not too much.