Abstract: The photovoltaic conversion systems based on photosynthesis have recently attracted much attention as alternative energy technology of the future. More interests are focused on the development of eco-friendly, cost-effective and safer dye-sensitized solar cells （DSSC）based on the principles and natural pigments of photosynthesis. Purple bacteria in anoxygenic phototrophic bacteria are good model systems for elucidating molecular mechanisms of photosynthesis. In this study, the photoelectrochemical properties of seven different natural photosynthetic pigments of bacteriochlorophyll a (BChl a) and carotenoids (Car) from Rhodopseudomonas palustris CQV97, Rhodobacter azotoformans R7 and Marichromatium sp. 283-1, and three modified BChl a derivatives were investigated in DSSC. The results showed that under the condition of simulated sunlight of 100 mW·cm^-2 intensity and without addition of spacer, natural BChl a of 0.48 mg·ml^-1 achieved better conversion efficiency of 1.26%. Purified rhodopin Car had higher conversion efficiency than that of mixture-Car and other purified Car. The absorption spectrum of TiO₂ electrode sensitized by BChl a red-shifted, and the fluorescence at 800 nm could be quenched, indicating that the electron ejected by BChl a entered TiO₂ conduction band. TiO₂ electrode sensitized by co-sensitization of BChl a and rhodopin exhibited wide spectrum response in visible light and near-infrared region, the photocurrent and conversion efficiency of co-sensitized solar cells increased by 12% and 7.3% compared to BChl a. The photosynthetic pigments from purple bacteria are inexpensive and environment friendly, and are promising dye sensitizers due to higher light-harvesting capacity in near-infrared region. This study provides valuable information for fabricating visible light-infrared responsive solar cells.

Key words: dye-sensitized solar cells, bacteriochlorophylls, carotenoids, purple bacteria

摘要： 基于自然界光合作用机理的DSSC研究备受关注。不产氧光合细菌中的紫细菌是研究光合作用机理的良好模式生物。从3种典型紫细菌中获得了7种具有不同吸光范围、极性和结构的细菌叶绿素a（BChl a）和类胡萝卜素（Car）以及3种改性BChl a。在此基础上，较系统地比较了天然与改性BChl a、多组分与单一组分Car、BChl a色素浓度、BChl a和Car共敏对DSSC光电性能的影响，并对色素与半导体材料的相互作用进行了表征。结果表明：100 mW·cm^-2入射光强下，在不添加任何分散剂（spacer）的条件下，具有近红外吸收的天然BChl a光电转化性能较优，光电转换效率为1.26%。单一组分Car比多组分Car具有较高的光电性能，玫红品Car光电转换效率最佳。BChl a敏化TiO₂薄膜电极，吸收光谱红移，800 nm特征荧光淬灭。BChl a与Car共敏TiO₂薄膜电极，拓宽了可见光吸收光谱，短路电流和光电转换效率比BChl a提高了12%和7.3%。紫细菌天然色素廉价易得、环境友好，不仅能吸收可见光，而且能有效利用红外光，这对研制响应可见光-近红外的太阳能电池光电器件具有重要参考价值。

关键词: 染料敏化太阳能电池, 细菌叶绿素, 类胡萝卜素, 紫细菌