Borgström Magnus, Blart Errol, Boschloo Gerrit, Mukhtar Emad, Hagfeldt Anders, Hammarström Leif, Odobel Fabrice
Department of Physical Chemistry, Uppsala University, Box 579, SE-751 23 Uppsala, Sweden.
J Phys Chem B. 2005 Dec 8;109(48):22928-34. doi: 10.1021/jp054034a.
This paper describes the preparation and the characterization of a photovoltaic cell based on the sensitization of a wide band gap p-type semiconductor (NiO) with a phosphorus porphyrin. A photophysical study with femtosecond transient absorption spectroscopy showed that light excitation of the phosphorus porphyrin chemisorbed on NiO particles induces a very rapid interfacial hole injection into the valence band of NiO, occurring mainly on the 2-20 ps time scale. This is followed by a recombination in which ca. 80% of the ground-state reactants are regenerated within 1 ns. A photoelectrochemical device, prepared with a nanocrystalline NiO electrode coated with the phosphorus porphyrin, yields a cathodic photocurrent indicating that electrons indeed flow from the NiO electrode toward the solution. The low incident-to-photocurrent efficiency (IPCE) can be rationalized by the rapid back recombination reaction between the reduced sensitizer and the injected hole which prevents an efficient regeneration of the sensitizer ground state from the iodide/triiodide redox mediator. To the best of our knowledge, this work represents the first example of a photovoltaic cell in which a mechanism of hole photoinjection has been characterized.
本文描述了一种基于用磷卟啉敏化宽带隙p型半导体（NiO）的光伏电池的制备及其表征。用飞秒瞬态吸收光谱进行的光物理研究表明，化学吸附在NiO颗粒上的磷卟啉的光激发会诱导非常快速的界面空穴注入到NiO的价带中，主要发生在2 - 20皮秒的时间尺度上。随后是一个复合过程，其中约80%的基态反应物在1纳秒内再生。用涂有磷卟啉的纳米晶NiO电极制备的光电器件产生阴极光电流，表明电子确实从NiO电极流向溶液。低的入射到光电流效率（IPCE）可以通过还原敏化剂与注入空穴之间快速的反向复合反应来解释，该反应阻止了敏化剂基态通过碘化物/三碘化物氧化还原介质的有效再生。据我们所知，这项工作代表了首个对空穴光注入机制进行了表征的光伏电池实例。
