光诱导电子注入染料敏感化TiO2的温度独立性由ab initio时间域密度函数理论合理化
Walter R Duncan1, Oleg V Prezhdo
1Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, USA.
Journal of the American Chemical Society
|July 3, 2008
概括
时间域密度函数理论模拟表明,虽然染料敏感太阳能电池中的电子转移 (ET) 动态略微依赖温度,但整体界面ET在很大程度上独立于温度.
科学领域:
- 计算化学是一种计算化学.
- 材料科学是一种材料科学.
- 太阳能光伏发电是如何实现的
背景情况:
- 染料敏感太阳能电池 (DSSC) 依赖于高效的电子转移 (ET) 从光激发染料到半导体电极,如二氧化 (TiO2).
- 关于热波动对ET速率的影响存在长期争论,一些研究表明它起着重要作用,而另一些研究则表明温度独立.
研究的目的:
- 解决关于DSSC中光诱导ET的温度依赖性的明显冲突.
- 为了阐明热波动在染色体-TiO2接口上的附加性和非附加性ET过程中的作用.
主要方法:
- 时间域密度函数理论 (TD-DFT) 模拟被用于模拟一个温度范围内的阿利沙林-TiO2接口.
- 分析包括adiabatic和非adiabaticET动态,过渡状态 (TS) 理论和费米的黄金规则.
主要成果:
- 和非的ET率都表现出轻微的温度依赖.
- 由于增强的过渡状态波动,阿迪亚巴特ET速率随着温度的增加而增加.
- 由于光激发状态能量分布的变化和可访问的TiO2能量水平,非增性ET速率随着温度的增加而增加.
结论:
- 研究的阿利沙林-TiO2系统具有强的合和导电带边缘附近的兴奋状态,主要显示亚亚巴特ET,温度略有依赖.
- 外推表明,DSSC中的界面ET通常是温度独立的,尽管热运动会影响初始条件和电子能量分布.
相关概念视频
02:26Photoelectric Effect
When light of a particular wavelength strikes a metal surface, electrons are emitted. This is called the photoelectric effect. The minimum frequency of light that can cause such emission of electrons is called the threshold frequency, which is specific to the metal. Light with a frequency lower than the threshold frequency, even if it is of high intensity, cannot initiate the emission of electrons. However, when the frequency is higher than the threshold value, the number of electrons ejected...
01:26Thermal and Photochemical Electrocyclic Reactions: Overview
Electrocyclic reactions are reversible reactions. They involve an intramolecular cyclization or ring-opening of a conjugated polyene. Shown below are two examples of electrocyclic reactions. In the first reaction, the formation of the cyclic product is favored. In contrast, in the second reaction, ring-opening is favored due to the high ring strain associated with cyclobutene formation.
01:26Photochemical Electrocyclic Reactions: Stereochemistry
The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation
Selection Rules: Photochemical Activation