Preferential Direction of Electron Transfers at a Dye–Metal Oxide Interface with an Insulating Fluorinated Self-Assembled Monolayer and MgO
Preferential Direction of Electron Transfers at a Dye–Metal Oxide Interface with an Insulating Fluorinated Self-Assembled Monolayer and MgO
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DOI：
10.1021/acs.jpcc.1c07981
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发表时间：
2021-11
期刊：
影响因子：
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通讯作者：
Leigh Anna Hunt;Roberta R. Rodrigues;Kayla Foell;Dinesh Nugegoda;Hammad Cheema;N. Hammer;J. Delcamp
中科院分区：
文献类型：
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作者：
Leigh Anna Hunt;Roberta R. Rodrigues;Kayla Foell;Dinesh Nugegoda;Hammad Cheema;N. Hammer;J. Delcamp
减缓金属氧化物-染料界面处的不期望的电子转移反应对于许多技术是重要的。特别地，在金属氧化物-染料界面处的界面光致电荷分离事件之后，限制电子转移反应回到敏化剂的速率和限制电解质与金属氧化物之间的电子转移反应是至关重要的。金属氧化物界面处的钌基染料广泛用于许多领域;然而，这些染料通常具有差的表面绝缘性，导致与电解质中的过渡金属基氧化还原梭（RS）的快速复合动力学。本工作探讨了两种半导体表面改性策略，旨在最大限度地减少电子在二氧化钛与氧化RS使用氟化硅氧烷绝缘体（PFTS）和金属氧化物绝缘体（MgO）与众所周知的Ru染料，B11的复合事件。此外，这些处理的影响的光致界面电荷分离的速率和持续时间在TiO 2-染料界面进行了检查。通过染料敏化太阳能电池的电流-电压曲线、入射光-电流转换效率、小调制光电压瞬态、时间相关单光子计数和瞬态吸收光谱测量研究了TiO 2-染料-RS体系。发现MgO降低了从金属氧化物到电解质的电子转移反应的速率，降低了从TiO 2到氧化染料的电子转移反应的速率，增加了从还原RS到氧化染料的电子转移反应速率，并降低了从光激发染料到TiO 2的电子注入速率。有趣的是，发现1H，1H，2 H，2 H-全氟辛基三甲氧基硅烷（PFTS）相对于MgO或未处理的TiO 2理想地改善这些速率。提出了一个基于静电相互作用的模型来解释PFTS的异常行为，并对PFTS进行了密度泛函理论计算分析。
Slowing nondesirable electron transfer reactions at metal oxide–dye interfaces is important for many technologies. In particular, after an interfacial photoinduced charge separation event at a metal oxide–dye interface, it is critically important to limit the rate of electron transfer reactions back to sensitizers and to limit electron transfer reactions between the electrolyte and the metal oxide. Ruthenium-based dyes at metal oxide interfaces are widely used in many fields; however, these dyes often have poor surface insulation resulting in fast recombination kinetics with transition metal-based redox shuttles (RSs) in an electrolyte. This work explores two semiconductor surface modification strategies designed to minimize recombination events of electrons in TiO2with oxidized RSs using a fluorinated siloxane insulator (PFTS) and a metal oxide insulator (MgO) with a well-known Ru dye,B11. Additionally, the influence of these treatments on the rate and duration of photoinduced interfacial charge separation at the TiO2–dye interface was examined. The TiO2-dye-RS systems were studied via dye-sensitized solar cell current–voltage curve, incident photon-to-current conversion efficiency, small modulated photovoltage transient, time-correlated single-photon counting, and transient absorption spectroscopy measurements. MgO was found to decrease the rate of the electron transfer reaction from the metal oxide to the electrolyte, decrease the rate of the electron transfer reaction to the oxidized dye from TiO2, increase the electron transfer reaction rate from a reduced RS to an oxidized dye, and decrease the electron injection rate from the photoexcited dye to TiO2. Interestingly, 1H,1H,2H,2H-perfluorooctyltrimethoxysilane (PFTS) was found to desirably improve these rates relative to MgO or untreated TiO2. A model based on electrostatic interactions is presented to explain the exceptional behavior of PFTS with density functional theory computational analysis of PFTS supporting this model.