Theory of soft and disordered excitonic nano-materials.

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Soft and disordered nano-materials with non-trivial electronic properties are a `terra incognita' of molecular science and engineering. Although there are ongoing serious attempts to understand and manipulate their behavior, this class of materials presents a considerable challenge to both experiment and theory, and little is firmly known about them. For example, amorphous pi-conjugated polymers, and optically or magnetically responsive proteins fall into this category. Their mechanical flexibility, biological compatibility, proteins' responsiveness to external stimuli, and the sensitivity of the morphology of amorphous polymers to external conditions, make them promising candidates for applications in energy, medical and electronics industries. The design of devices for such applications is, however, hindered by the fact that in most cases the underlying molecular mechanisms are not known. My research program aims to model and explain the behavior of electronic excitations in large and disordered polymeric systems in which molecular level disorder is not a perturbation but the entire story. As my first step, I will construct a custom computational platform for the multi-scale quantum/classical hybrid simulation of such systems where existing state of the art methods will be complemented by new methods developed in my group. My innovation efforts will be focused on: 1. methods for sampling device-scale configurations of aggregates of polymers by leveraging the emerging machine learning algorithms and computational architectures; 2. algorithms for the dynamics of photo-excitations in two challenging scenarios: a. for very large but weakly correlated electronic systems, and b. for small but strongly correlated electronic systems embedded in polarizing environments of interest. I will then use these computational tools to perform computational experiments which will help us identify the characteristic behaviors of key complex systems, explain experimental observations which cannot be explained without sufficient molecular level insight, and finally conceptualize the effects of morphology on the dynamics and the fate of photo-excitations in this class of materials. This research is poised to develop the conceptual vocabulary for strongly disordered optoelectronic matter and help unlock the potential of organic and bio- electronics.