Ab Initio Design of 2D Hybrid Organohalide Perovskites with Tunable Band Gap
Maurizio Cossi a, Alberto Fraccarollo a, Leonardo Marchese a
a Università del Piemonte Orientale “A. Avogadro”, Viale T. Michel 11, Alessandria, 15121, Italy
nanoGe Perovskite Conferences
Proceedings of International Conference on Perovskite Thin Film Photovoltaics, Photonics and Optoelectronics (ABXPV18PEROPTO)
Perovskite Thin Film Photovoltaics (ABXPV18). 27-28 Feb
Rennes, France, 2018 February 27th - March 1st
Organizer: Jacky Even
Oral, Maurizio Cossi, presentation 009
DOI: https://doi.org/10.29363/nanoge.abxpvperopto.2018.009
Publication date: 11th December 2017

Different series of layered perovskites, based on lead and tin tetrahalide sheets intercalated by organic cations, are modeled with ab initio techniques. The structures are optimized at the DFT level, with inclusion of dispersion contributions, in several symmetry groups or without symmetry constraints.

The electronic properties (mainly, band structures and gaps) are computed at the state-of-the-art level with inclusion of spin-orbit-coupling (SOC) and post-DFT (GW) corrections.

A number of structure/properties relationships are discussed: in particular, we describe how the nature of the intercalated cations influences the perovskite band gap either directly or indirectly (through geometrical changes, e.g. to the interlayer distance).

Then we can sketch what combination of inorganic and organic counterparts can be used to select the desired electronic properties.

For photovoltaic applications, the computed band gaps of these layered systems are often too large. However, some of the modeled systems exhibit smaller gaps, sometimes as low as 1.4 eV, due to the electronic effects of suitable doubly charged cations: we discuss such effects, as well as effective molecular descriptors to predict the formation of such low band gap perovskites.

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