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Condensed Matter Seminar "Electronic structure theory for 2d hybrid organic-inorganic perovskites"
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Thursday, April 2, 2020 - 11:30am to 12:00pm
Volker Blum (Duke University)
Layered 2d hybrid organic-inorganic perovskites (HOIPs) can be created by combining a wide range of possible inorganic components with an even broader range of organic molecules, offering considerable flexibility to fine-tune their synthesizability and properties. This talk focuses on computational predictions of the electronic energy levels of new 2d HOIP materials. Such predictions pose a considerable challenge due to high required levels of theory and large unit cells (hundreds of atoms) associated with typical 2d HOIPs. We here use high-precision, all-electron hybrid density functional theory including spin-orbit coupling, showing that this combination provides descriptions of the quantum-well like energy level alignment in lead halide based oligothiophene perovskites in excellent agreement with experiments. We then employ the same approach to predictively address the electronic properties of a broad range of further 2d HOIPs, including lead-free (Ag-Bi) based ones. As a final point, we show that the details of the atomic structure used to predict electronic properties matter significantly, even in a qualitative sense, by determining energy level alignments and, therefore, which component (organic or inorganic) forms the band edges. A complete structural understanding of a given target 2d HOIP is thus essential for faithfully predicting the properties that can be leveraged within this promising new semiconductor materials space.