Tuning the Electronic Structure of Perovskites via Composition - A Combined Theoretical and Experimental Approach
Selina Olthof a b, Shuxia Tao c, Geert Brocks d
a University of Cologne, Institute for Physical Chemistry, Luxemburgerstrasse 116, Köln, 50939, Germany
b Shaanxi Normal University, Engineering Lab for Advanced Energy Technology
c Eindhoven University of Technology, Center for Computational Energy Research
d University of Twente, Faculty of Science and Technology and MESA+ Institute for Nanotechnology,
nanoGe Perovskite Conferences
Proceedings of International Conference on Perovskite Thin Film Photovoltaics and Perovskite Photonics and Optoelectronics (NIPHO20)
Sevilla, Spain, 2020 February 23rd - 25th
Organizer: Hernán Míguez
Oral, Selina Olthof, presentation 006
Publication date: 25th November 2019

The interest in halide perovskites is rising at a rapid pace due to their tremendous success as solution processable, high quality semiconductor for optoelectronic applications. One intriguing property of this material class is the wide range of the possible band-gaps, which can be tuned by changing the perovskite composition.

While such changes in band gap are regularly reported, it is unclear how the respective conduction and valence band positions change and little is understood about the origins of these changes. Knowing the positions of valence and conduction band is however crucial for device design.

To tackle this issue, we use a combination of photoelectron spectroscopy and density functional theory to reliably extract the relevant energy level positions. Furthermore, employing a tight binding model, we are able to explain the origin of these changes based on changes in hybridization strength, atomic level positions, and lattice distortion.

This approach allows us to present the complete set of energy levels for the 3D lead and tin based halide perovskite. [1] In this talk, the focus will be on “pure” systems, but we also show some more recent results on mixed cation or mixed anion materials.

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