Research

When molecules crystallise, they typically form non-porous structures to maximise the intermolecular interactions. Porosity in molecular crystals can be observed when (1) the molecules have directional intermolecular interactions, such as hydrogen bonding (2) the shape of the molecule hinders efficient packing, or (3) the molecules themselves are porous, containing an internal cavity, such as porous- and metal-organic cages. Predicting whether these molecules will form porous molecular crystals is a non-trivial task and small changes in a molecules functionality can lead to large, non-intuitive changes in their solid-state phase behaviour. My research seeks to understand the interplay between molecular shape and interactions in the formation of porous molecular crystals by creating simple, toy models with the molecules represented as hard shapes with directional interactions between favoured packing motifs. Using atomistic calculations between dimers of molecules, we can parameterise the models for ab initio crystal structure prediction and use this principle to understand how to introduce emergent phenomena into materials, such as chirality. Moreover, by manipulating the parameters of our models beyond known systems, we can understand how changing chemical features of our molecules can affect the packing behaviour, informing design rules for targeted crystal structures. 

Organic electronic devices have promise in innovative applications such as wearable technologies, low-power displays, and smart packaging. These devices represent a vital step towards an energy-aware future as they offer more sustainable and energy-efficient alternatives to many current electronic devices. But despite their potential, the use of organic electronics has been confined to certain applications such as displays in TV and smartphones. One major challenge is controlling the orientation of molecules within devices, as the the molecular orientation has a dramatic effect on the device performance. Solid surfaces can act as a template to alter the orientation of molecules within devices, but predicting the outcome of surface/molecule combinations is a complex task and so surfaces are usually selected through trial and error, which is both time and resource intensive. My research addresses this challenge by developing simple models which enable fast simulations with low computational cost to explore the effect of surfaces on molecular assembly.

Layered materials have applications in many important functional materials such as batteries, membranes, and electronics. They usually have anisotropic properties due to the strong intralayer interactions through covalent or ionic bonding, but weak interlayer interactions dominated by non-covalent interactions such as van der Waals and electrostatic interactions. These week interlayer interactions result in stacking disorder in many layered materials e.g. transition-metal cyanides, 2D covalent- and metal-organic frameworks, and graphite. The disorder in each of these materials can have a profound consequence on the materials properties. My research looks to develop statistical mechanical models to understand the driving forces leading to stacking disorder in layered materials, while also providing a route to create atomistic structures for downstream property predictions of the materials.

Deviations from long-range order have been known to play a key role in fundamental properties since the 1950s. Disorder is known to exist in many functional materials and greatly influence materials’ behaviour, even enhancing their properties. Disorder does not necessarily imply randomness and many phases exist which exhibit short-range order and long-range disorder. Such phases are described as containing correlated disorder and may even be more common than crystalline phases in simple systems such as the dense packings of simple polyhedra. My interest is in disorder in materials which arise due to structural degrees of freedom e.g. composition and orientational disorder. Using simple models we can begin to understand, (1) the driving forces of disorder, (2) the effect of the disorder on the materials properties, and (3) how disorder can be used to introduce complexity and functionality into materials.