Research Center for Organic Electronics, Graduate School of Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa, Yamagata 992-8510, Japan.
Molecules. 2012 Apr 13;17(4):4484-97. doi: 10.3390/molecules17044484.
Natural-chlorophyll-related porphyrins, including (2H, Zn, Cu)-protoporphyrin IX (Por-1) and Zn-mesoporphyrin IX (Por-2), and chlorins, including chlorin e₆ (Chl-1), chlorin e₄ (Chl-2), and rhodin G₇ (Chl-3), have been used in dye-sensitized solar cells (DSSCs). For porphyrin sensitizers that have vinyl groups at the β-positions, zinc coordinated Por-1 gives the highest solar-energy-to-electricity conversion efficiency (h) of up to 2.9%. Replacing the vinyl groups of ZnPor-1 with ethyl groups increases the open-circuit voltage (V(oc)) from 0.61 V to 0.66 V, but decreases the short-circuit current (J(sc)) from 7.0 mA·cm⁻² to 6.1 mA·cm⁻² and the value of h to 2.8%. Density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations suggest that the higher J(sc) values of Zn-based porphyrin sensitizers result from the favorable electron injection from the LUMO at higher energy levels. In the case of the chlorin sensitizers, the number of carboxyl protons has a large effect on the photovoltaic performance. Chl-2 with two carboxyl protons gives much higher values of J(sc), V(oc), and h than does Chl-1 with three carboxyl protons. Replacing the protons of Chl-1 with sodium ions can substantially improve the photovoltaic performance of Chl-1-based solar cells. Furthermore, the sodium salt of Chl-3 with an aldehyde group at the C7 position shows poorer photovoltaic performance than does the sodium salt of Chl-1 with methyl groups at the C7 position. This is due to the low light-harvesting capability of Chl-3.
天然叶绿素相关卟啉，包括（2H，Zn，Cu）-原卟啉 IX（Por-1）和 Zn-中卟啉 IX（Por-2），以及叶绿素，包括叶绿素 e₆（Chl-1），叶绿素 e₄（Chl-2）和 Rhodin G₇（Chl-3），已被用于染料敏化太阳能电池（DSSC）。对于β位具有乙烯基基团的卟啉敏化剂，锌配位的 Por-1 给出高达 2.9%的最高太阳能到电能转换效率（h）。用乙基取代 ZnPor-1 的乙烯基基团会将开路电压（V(oc)）从 0.61 V 提高到 0.66 V，但会将短路电流（J(sc)）从 7.0 mA·cm⁻²降低到 6.1 mA·cm⁻²，并且 h 值降低到 2.8%。密度泛函理论（DFT）和时间相关 DFT（TD-DFT）计算表明，Zn 基卟啉敏化剂具有较高的 J(sc)值，这是由于高能级的 LUMO 有利于电子注入。在叶绿素敏化剂的情况下，羧基质子的数量对光电性能有很大影响。具有两个羧基质子的 Chl-2 给出的 J(sc)、V(oc)和 h 值远高于具有三个羧基质子的 Chl-1。用钠离子取代 Chl-1 的质子可以显著提高基于 Chl-1 的太阳能电池的光电性能。此外，在 C7 位具有醛基的 Chl-3 的钠盐的光电性能比在 C7 位具有甲基的 Chl-1 的钠盐差。这是由于 Chl-3 的光收集能力低。
