基于咔唑供体的敏化染料的合成及其光电性质

Synthesis and Photoelectric Properties of Dye Sensitizer Based on Carbazole as Donor

以咔唑为供体,设计并合成了具有D-A-π-A或D-π-A结构的有机敏化染料2-氰基-3-{5-[7-(9-己基咔唑-3-基)-苯并[1,2,5]噻二唑-4-基]-2-噻吩基}-丙烯酸(CVBTC)和2-氰基-3-{5-[7-(9-己基咔唑-3-基)]-2-噻吩基}-丙烯酸(CVHTC)。研究了结构变化对敏化染料的光物理性质、电化学性质和光伏性能的影响。研究表明,在染料CVHTC的D-π-A结构链上插入受体苯并噻二唑单元,得到的具有D-A-π-A结构的染料CVBTC的共轭体系变大,带隙变小,光吸收性能得到明显提升。CVBTC和CVHTC的HOMO能级分别为-5.24和-5.52eV,LUMO能级分别为-3.20和-2.88eV,均能与常见电解质I-/I3-(-4.60eV vs vacuum)以及TiO2导带能级(-4.40eV vs vacuum)相匹配,都可用作DSSCs的敏化染料。并且与CVHTC相比,具有D-A-π-A结构CVBTC,因苯并噻二唑单元的引入,其光电池的短路电流和光电转换效率均得到明显提升。

Two organic dyes 2-cyano-3-(5-(7-(9-hexyl-carbazole-3-yl)benzo[1,2,5]thiadiazol-4-yl)thiophen-2-yl)acrylic acid(CVBTC)and 2-cyano-3-(5-(9-hexyl-carbazole-3-yl)thiophen-2-yl)acrylic acid(CVHTC)based on carbazole with D-A-π-A or D-π-A formation were designed and synthesized for dye sensitized solar cells(DSSCs),respectively.The effects of the structure changes on the photophysical,electrochemical and photovoltaic properties of DSSCs were investigated.The investigation showed that the dye CVBTC,introduced by an additional electron-deficient benzothiadiazole unit,had a larger conjugated system and a lower band gap,and its light absorption performance was improved significantly.The HOMO levels of the CVBTC and CVHTC are-5.24 and-5.52 eV and the LUMO levels were-3.20 and-2.88 eV,respectively.Both of the CVBTC and the CVHTC are matched with common electrolyte I^-/I^-3(-4.60 eV vs vacuum)and TiO_2 conduction band energy level(-4.40 eV vs vacuum).Thus they are all available as dye senstizers for DSSCs.In comparison with CVHTC,the photocurrent density and photoelectric conversion efficiency of CVBTC are obviously improved due to the D-A-π-A structure introduced by benzoxadiazole units.