Charge transfer between adsorbed dyes and the TiO₂ surface plays a key role in controlling the efficiency of dye-sensitized solar cells (DSSCs). The lack of understanding of charge transfer steps has hindered further development of DSSCs and many solar energy conversion devices/processes. In this study, we used in situ infrared spectroscopy to investigate electron transfer and photo-electric energy conversion processes at the interface, i.e., surface hydroxyls, adsorbed species, as well as the dynamics of photo-generated electrons in TiO₂ and N-TiO₂ in DSSCs. Nitrogen (N-) doping of TiO₂ blocked linear OH, giving more hydrophobic surface characteristics than undoped TiO₂. N-Doping further increased the electron–hole separation caused by solar light on the working electrode and the current density in the DSSC. In situ infrared (IR) studies revealed that N-doping facilitated the electron transfer from the N719 dye (di-tetrabutylammonium cis-bis(isothiocyanato)bis(2,2-bipyridyl-4,4-dicarboxylato)ruthenium(II)) to the conduction band in TiO₂, reducing the impedance in the DSSC. Probing N-TiO₂ with adsorbed ethanol showed that shallow traps in N-TiO₂ can be accessed by electrons from adsorbed ethanol. Electron transfer from the N719 dye is significantly faster than that from adsorbed ethanol which involves C–H bond breaking.

中文翻译：

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染料敏化太阳能电池中氮掺杂的TiO ₂上光生电子和吸附物质的原位红外研究†

吸附的染料与TiO ₂表面之间的电荷转移在控制染料敏化太阳能电池（DSSC）的效率方面起着关键作用。对电荷转移步骤缺乏了解阻碍了DSSC和许多太阳能转化装置/工艺的进一步发展。在这项研究中，我们使用原位红外光谱技术研究了界面处的电子转移和光电能量转换过程，即表面羟基，吸附物质以及TiO ₂和N-TiO中光生电子的动力学。DSSC中为₂。TiO _2的氮（N-）掺杂可阻止线性OH，比未掺杂的TiO具有更多的疏水表面特性₂。N掺杂进一步增加了工作电极上的太阳光和DSSC中的电流密度引起的电子-空穴分离。原位红外（IR）研究表明，N掺杂促进了电子从N719染料（顺式二丁基四铵铵-双（异硫氰酸根）双（2,2-联吡啶基-4,4-二羧基甲酰基）钌（ II））转移到电子TiO _2中的导带，降低了DSSC中的阻抗。用吸附的乙醇探测N-TiO ₂显示，N-TiO ₂中的浅陷阱可以被吸附的乙醇中的电子进入。N719染料的电子转移明显快于涉及C–H键断裂的吸附乙醇。