Structure Prediction of Ionic Epitaxial Interfaces with Ogre Demonstrated for Colloidal Heterostructures of Lead Halide Perovskites

TL;DR

This paper introduces Ogre, a computational tool for predicting and analyzing ionic epitaxial interfaces in colloidal heterostructures, validated on lead halide perovskite systems, aiding in the design of novel nanomaterials.

Contribution

Ogre provides an efficient, automated method for predicting epitaxial interfaces between ionic materials, validated against DFT and experimental data, advancing colloidal heterostructure design.

Findings

Ogre accurately predicts interface structures consistent with DFT and experiments.

It rationalizes templating effects in heterostructure growth.

It helps assign structures to previously unresolved interfaces.

Abstract

Colloidal epitaxial heterostructures are nanoparticles composed of two different materials connected at an interface, which can exhibit properties different from those of their individual components. Combining dissimilar materials offers opportunities to create several functional heterostructures. Yet, assessing structural compatibility (the main prerequisite for epitaxial growth) is challenging when pairing complex materials with different lattice parameters/crystal structures. This complicates both the selection of target heterostructures for synthesis and the assignment of interface models when new heterostructures are obtained. Here, we demonstrate Ogre as a powerful tool to accelerate the design and characterization of colloidal heterostructures. To this end we implemented developments tailored for the efficient prediction of epitaxial interfaces between ionic/polar materials, which encompass most colloidal semiconductors. These include pre-screening candidate models based on charge balance at the interface and using a classical potential for fast energy evaluations, with parameters automatically extracted from the input bulk structures. These developments are validated for CsPbBr3/Pb4S3Br2 heterostructures, where Ogre produces interface models in agreement with density functional theory and experiments. Furthermore, we use Ogre to rationalize the templating effect of CsPbCl3 on the growth of lead sulfochlorides, where perovskite seeds induce the formation of Pb4S3Cl2 rather than Pb3S2Cl2 due to better epitaxial compatibility. Combining Ogre simulations with experimental data enables us to unravel the structure and composition of the hitherto unsolved CsPbBr3/BixPbySz interface and assign a structure to many other reported metal halide/oxide based interfaces. The Ogre package is available on GitHub or via the OgreInterface desktop application, available for Windows, Linux and Mac.