UNDERPIN: UNDERstanding quantum Properties of Interfaces from first principles

在光伏领域，现在很清楚，现有技术的优化和新技术的开发需要更好地控制界面的物理特性。在任何控制策略的基础上，都需要深刻理解所涉及的不同物理现象及其相互依存关系。本研究旨在通过从头计算确定界面形态与电子-空穴动力学之间的相互作用，以便更好地了解太阳能电池界面上控制电荷分离和重组的机制。为此，我们将与实验伙伴密切合作，重点研究与光伏相关的各种异质界面，包括Cu(Ga, in)Se2/CdS和Cu(Ga, in)Se2/背接触结，Cu2ZnSnSe4和二次相之间的界面，以及钙钛矿吸收剂和电子/空穴传输层之间的界面。在广义密度泛函理论和时变密度泛函理论的框架下，我们正在开发一种新的局部混合泛函，该泛函来源于GW理论，旨在通过依赖于局部介电函数的密度估计量来解释电子屏蔽。该功能将在简单界面上进行进一步测试，实验数据可用，然后用于计算太阳能电池器件中实际界面的电子激发。由于我们的新杂化函数，我们将对电子-空穴输运、分离和复合有决定性的理解。通过揭示能量转换的限制因素，我们将最终能够提出如何克服这些限制的建议。这个项目是我最近成立的小组雄心勃勃的长期战略的一部分，它将对加强现有的合作和促进与欧洲光伏实验家的新合作产生有益的影响。

In the domain of photovoltaics it is by now clear that the optimization of existing technologies and the development of new ones passes through a better control of the physics of interfaces. At the basis of any control strategy lies the need for a deep understanding of the different physical phenomena involved and their interdependence. This proposal aims at determining by means of ab initio calculations the interplay between interface morphology and electron-hole dynamics, in order to understand better the mechanisms controlling charge separation and recombination at interfaces in solar cells.To this end, in close collaboration with experimental partners, we will focus on a variety of hetero-interfaces relevant for photovoltaics, including Cu(Ga,In)Se2/CdS and Cu(Ga,In)Se2/back contact junctions, interfaces between Cu2ZnSnSe4 and secondary phases, as well as between perovskite absorbers and electron/hole transport layers.In the framework of generalized density functional theory and time-dependent density functional theory, we are developing a new local hybrid functional, derived from GW theory, and designed to account for electronic screening through its dependence on a density estimator of the local dielectric function. This functional will be further tested on simple interfaces, for which experimental data are available, and then used to calculate electronic excitations at realistic interfaces in solar cell devices. Thanks to our new hybrid functional, we will gain decisive understanding on electron-hole transport, separation and recombination. By shedding light on the limiting factors for energy conversion, we will finally be able to bring suggestions on how to overcome these limitations.This project is part of an ambitious long-term strategy in my recently established group and it will have the beneficial consequence to strengthen existing collaborations and promote new ones with experimentalists working on photovoltaics in Europe.