Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27514, United States.
ACS Appl Mater Interfaces. 2017 Aug 16;9(32):26786-26796. doi: 10.1021/acsami.7b05856. Epub 2017 Aug 1.
The hole-injection and recombination photophysics for NiO sensitized with RuP ([Ru(bpy)(4,4'-(POH)-bpy)]) are explored. Ultrafast transient absorption (TA) measurements performed with an external electrochemical bias reveal the efficiency for productive hole-injection, that is, quenching of the dye excited state that results in a detectable charge-separated electron-hole pair, is linearly dependent on the electronic occupation of intragap states in the NiO film. Population of these states via a negative applied potential increases the efficiency from 0% to 100%. The results indicate the primary loss mechanism for dye-sensitized NiO is rapid nongeminate recombination enabled by the presence of latent holes in the surface of the NiO film. Our findings suggest a new design paradigm for NiO photocathodes and devices centered on the avoidance of this recombination pathway.
研究了 RuP([Ru(bpy)(4,4'-(POH)-bpy)])敏化 NiO 的空穴注入和复合光物理。通过外加电化学偏压进行超快瞬态吸收（TA）测量，揭示了产生空穴注入的效率，即染料激发态的猝灭导致可检测的电荷分离电子-空穴对的效率，与 NiO 薄膜中间隙态的电子占据线性相关。通过施加负向偏压来填充这些状态，可以将效率从 0%提高到 100%。结果表明，敏化 NiO 的主要损耗机制是由 NiO 薄膜表面潜在空穴的存在而导致的快速非辐射复合。我们的发现为基于避免这种复合途径的 NiO 光电阴极和器件提出了一个新的设计范例。
