Dye-sensitized solar cells (DSSCs) are a promising third-generation photovoltaic cell technology whose advantages are low-cost fabrication, reduced energy payback time, better performance under diffuse light conditions and flexibility. Typically DSSCs employ toxic dyes such as metal-based porphyrins requiring complex synthesis. In contrast, natural pigments are environmentally and economically superior to synthetic dyes. However, narrow absorption spectra of natural pigments result in low efficiencies of the solar cells. Hence, co-sensitizing pigments with complementary absorption spectra, which increases the absorption band, is an attractive pathway to enhance the efficiency. In this paper, we report the performance of betanin–chlorophyll co-sensitized solar cell using betanin (λ_max = 535 nm) and chlorophyll-a (λ_max = 435 nm, 668 nm), natural pigments having complementary absorption spectra. Density functional theory simulations were performed to verify that the lowest unoccupied molecular orbital and the highest occupied molecular orbital levels of the dye molecules, are aligned appropriately with that of TiO₂ and the redox electrolyte, respectively, which is necessary for optimal device performance. Electrochemical impedance spectroscopic studies were performed to determine parameters corresponding to the charge transfer processes in the dye solar cells. Individual and co-sensitized solar cells were fabricated and the co-sensitized solar cell demonstrated a higher efficiency of 0.601% compared to efficiencies of 0.562% and 0.047% shown by betanin and chlorophyll solar cells, respectively.

中文翻译：

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协同增敏有助于提高甜菜碱-叶绿素太阳能电池的效率

染料敏化太阳能电池（DSSC）是一种很有前途的第三代光伏电池技术，其优势在于低成本的制造，减少的能源回收时间，在漫射光条件下的更好性能和灵活性。通常，DSSC使用需要复杂合成的有毒染料，例如金属基卟啉。相反，天然颜料在环境和经济上优于合成染料。然而，天然颜料的窄吸收光谱导致太阳能电池的低效率。因此，具有互补吸收光谱的共增感颜料会增加吸收带，这是提高效率的诱人途径。在本文中，我们用甜菜苷（报告甜菜苷的叶绿素共同敏化太阳能电池的性能λ_最大 = 535纳米）和受叶绿素一个（λ_最大 = 435纳米，668纳米），具有互补的吸收光谱的天然色素。进行密度泛函理论仿真，以验证染料分子的最低未占据分子轨道和最高占据分子轨道能级与TiO ₂适当对齐和氧化还原电解质，分别是实现最佳器件性能所必需的。进行了电化学阻抗谱研究，以确定与染料太阳能电池中的电荷转移过程相对应的参数。制备了单独的和共增感的太阳能电池，与分别由甜菜碱和叶绿素的太阳能电池显示的效率为0.562％和0.047％相比，该增感太阳能电池显示出0.601％的更高效率。