香豆素型染料敏化剂的合成及光电性能研究

Synthesis and Photoelectric Properties of Coumarin Type Sensitizing Dyes

选择带有供电子基团的香豆素作为给体,噻吩基作为桥键,氰乙酸为受体,合成了两种新的具有"D-π-A"结构的香豆素型染料敏化剂,对其光谱性能、电化学性能以及光电转换性能进行了测试.结果表明,两者分子轨道能级与TiO2电极的导带以及电解质I2/I-的氧化还原电位相匹配,保证了电池电流循环的顺利产生.与甲氧基取代的染料敏化剂2-氰基-3-[5-(7-甲氧基-2-羰基-2H-苯并吡喃-3-基)噻吩-2-基]丙烯酸(IIIb)相比,香豆素环7位上二乙氨基取代的染料敏化剂2-氰基-3-[5-(7-二乙胺基-2-羰基-2H-苯并吡喃-3-基)噻吩-2-基]丙烯酸(IIIa)分子内电荷转移吸收较强,紫外吸收光谱红移.IIIa组装得到的染料敏化太阳能电池暗电流降低,具有较高的单色光转化效率IPCE(incident photo-to-currentconversion efficient)和短路电流Jsc,从而具有较高的光电转换效率(Jsc=8.68 mA/cm2,Voc=574 mV,η=3.52%).

Two novel coumarin type sensitizing dyes were synthesized with coumarin group bearing electron-donating group as donor, thiophene as n bridge and cyanoacetic acid as acceptor. Their spectral, electrochemical and photoelectric properties were evaluated. The results suggest that both dyes have the molecular orbital energy matched with the conduction band of TiO2 and the redox potential of the electrolyte I2/I-, which ensures the production of the current cycle in the cell. Compared with 2-cyano-3-[5-（7-methoxy-2-oxo-2H-chromen-3-yl）thiophen-2-yl]acrylic acid （IIIb） bearing methoxy group, sensitizing dye 2-cyano-3-[5-（7-diethylamino-2-oxo-2H-chromen-3-yl）thiophen-2-yl]acrylic acid （llIa） bearing diethylamino group on C-7 of coumarin ring shows improved absorption of intramolecular charge transfer and the red shift of UV spectra. Dye sensi- tized solar cell （DSSC） based on Ilia has reduced back current and better IPCE （incident photo-to-current conversion effi- cient） and Jsc, which leads to improved photoelectric conversion efficiency （Jsc= 8.68 mA/cm2, Voc= 574 mV,η=3.52%）.