Electronic structure and band gap tuning of perovskites from first principles
Thomas Körzdörfer and Norbert Koch
Organometallic perovskite solar cells have revolutionized the field of emerging photovoltaics, rapidly surpassing the performance of the conventional dye-sensitized and organic technologies. In addition to their favorable optoelectronic properties, perovskites are structurally and compositionally very flexible, which makes them ideal candidates for the application in tandem solar cells. Efficient tandem architectures, however, require the combination of materials with precisely tuned optoelectronic properties. Despite the extremely fast progress in recent years, relatively little is understood about the key electronic properties of perovskite-based solar cells and how they can be specifically tuned, e.g., by changing the compositional or structural properties.
The PhD-student working on this project will perform in-depth theoretical investigations of the electronic structure of perovskite materials using state-of-the-art electronic structure methods. The aim is to clarify how the key electronic properties of perovskites, such as the optical band gap, can be tuned by changing the composition and/or structures. It will be of central importance to gain a profound understanding of the key ingredients that affect the electrical, optical, and transport properties of these perovskite materials, thus, opening the way to the design of new and improved materials.
In terms of the methods, the student will mainly use density functional theory (DFT), time-dependent density functional theory (TD-DFT), and many-body perturbation theory calculations in the GW approximation (and beyond). Experience with any of these methods or, more generally, with electronic structure calculations for periodic systems would be helpful, yet not strictly required. While the focus of this work is theoretical, the student will be working closely together with the experimental projects associated with the graduate school. Not only will the insights from this theoretical work lead to a better understanding of the key electronic properties of perovskites, but its outcome will also yield important input towards the design of novel perovskite materials and help to identify ideal candidates for tandem cell applications. In summary, this is a very challenging but also very rewarding project, requiring an enthusiastic PhD candidate with a sound training in theoretical/computational physics or chemistry and interest in theoretical materials science.