Clifford John N, Forneli Amparo, López-Arroyo Leticia, Caballero Rubén, de la Cruz Pilar, Langa Fernando, Palomares Emilio
L1.1.6 Laboratory, Institute of Chemical Research of Catalonia (ICIQ), Avda. Països Catalans 16, Tarragona 43007, Spain.
ChemSusChem. 2009;2(4):344-9. doi: 10.1002/cssc.200900043.
Two new organic dyes have been synthesized and used as efficient light-harvesting materials in molecular photovoltaic devices. These dyes are based on conjugated thienylvinylene units, with FL-4 consisting of a four-unit thienylvinylene oligomer and its homologue FL-7 which additionally incorporates the electron-donating triphenylamine unit (TPA) into its structure. Upon light excitation both dyes show efficient electron injection into the TiO2 conduction band and slow back electron transfer to the oxidized dye. In fact, for FL-7, the back electron transfer dynamics are slower owing to efficient hole transfer to the TPA moiety situated further from the semiconductor surface. However, the electron recombination kinetics with the oxidized electrolyte for both FL-4 and FL-7 in dye-sensitized solar cells are faster than for devices made using the ruthenium dye N719. We believe that this is a serious limiting factor for devices based on oligothiophenes which, despite showing higher molecular extinction coefficients in the vis-NIR region of the solar spectrum, still cannot challenge the light-to-energy conversion efficiency of N719 or other ruthenium polypyridyl complexes.
两种新型有机染料已被合成，并用作分子光伏器件中高效的光捕获材料。这些染料基于共轭噻吩基亚乙烯基单元，其中FL-4由四单元噻吩基亚乙烯基低聚物组成，其同系物FL-7在其结构中额外引入了给电子三苯胺单元（TPA）。光激发时，两种染料都能有效地将电子注入TiO2导带，并缓慢地将电子反向转移到氧化态染料。事实上，对于FL-7，由于空穴有效地转移到距离半导体表面更远的TPA部分，反向电子转移动力学较慢。然而，染料敏化太阳能电池中FL-4和FL-7与氧化态电解质的电子复合动力学比使用钌染料N719制成的器件更快。我们认为，这是基于寡聚噻吩的器件的一个严重限制因素，尽管这些器件在太阳光谱的可见-近红外区域显示出更高的分子消光系数，但仍然无法挑战N719或其他钌多吡啶配合物的光-能转换效率。
