Electrons are the workhorses of solar energy conversion. Conversion of the energy of light to electricity in photovoltaics, or to energy-rich molecules (solar fuel) through photocatalytic processes, invariably starts with photoinduced generation of energy-rich electrons. The harvesting of these electrons in practical devices rests on a series of electron transfer processes whose dynamics and efficiencies determine the function of materials and devices. To capture the energy of a photogenerated electron–hole pair in a solar cell material, charges of opposite sign have to be separated against electrostatic attractions, prevented from recombining and being transported through the active material to electrodes where they can be extracted. In photocatalytic solar fuel production, these electron processes are coupled to chemical reactions leading to storage of the energy of light in chemical bonds. With the focus on the ultrafast time scale, we here discuss the light-induced electron processes underlying the function of several molecular and hybrid materials currently under development for solar energy applications in dye or quantum dot-sensitized solar cells, polymer–fullerene polymer solar cells, organometal halide perovskite solar cells, and finally some photocatalytic systems.

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太阳能转换中的超快电子动力学

电子是太阳能转换的主要力量。通过光催化过程将光能转换为电能，或通过光催化过程转换为能量丰富的分子（太阳能），总是以光诱导的方式产生能量丰富的电子开始。这些电子在实际设备中的收集取决于一系列电子转移过程，这些过程的动力学和效率决定了材料和设备的功能。为了在太阳能电池材料中捕获光生电子-空穴对的能量，必须将具有相反符号的电荷与静电引力分开，防止其重新结合并通过活性材料传输至电极，以便将其提取。在光催化太阳能燃料生产中，这些电子过程与化学反应耦合，导致光能以化学键的形式存储。着眼于超快时间尺度，我们在这里讨论光致电子过程，该过程是目前正在开发的几种分子和杂化材料的功能，这些材料用于染料或量子点敏化太阳能电池，聚合物-富勒烯聚合物太阳能电池中的太阳能，有机金属卤化物钙钛矿太阳能电池，最后是一些光催化系统。