Designing light-matter hybrid states for high-performance organic (opto)electronics

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Non-technical Description: Interactions between organic molecules and light may enable formation of a hybrid light-matter state (polariton). Such state has fascinating optical and electronic properties which are of interest both from the fundamental physics and from the applications perspective. The applications of polaritons include lasers, sensors, devices enabling optical communications and information processing, and many others. In this project, properties of polaritons are explored using a combination of experimental and computational approaches with the goal of designing next-generation organic optoelectronic materials and device architectures that utilize enhanced light emission and/or conductivity enabled by polaritons. The project integrates fundamental physics with materials design and device technologies, thus providing unique educational resources and infrastructure for graduate and undergraduate students, including those from underrepresented groups, involved in this project. The investigators develop educational materials based on the results of the project and related concepts and participate in a broad variety of outreach activities ranging between lab-based demonstrations for various audiences and participation in university-wide and department-wide outreach initiatives.Technical Description: Organic (opto)electronic materials are of interest due to their low cost and tunable properties appropriate a broad range of applications has been demonstrated. One of the areas that has seen a dramatic progress is the applications relying on strong exciton-photon coupling in organic microcavities. In spite of considerable amount of theoretical and experimental work on strong exciton-photon coupling in organic materials, there is still a number of unresolved fundamental issues pertaining to the nature and properties of hybrid light-matter (polariton) states. Resolving some of these issues and providing experimental validation for some of the recent theoretical predictions, exemplified by that of a dark polariton (a hybrid state with unique photophysical characteristics), is the goal of the present research. In particular, a systematic investigation of photophysics of hybrid light-matter states and their ability to enhance charge transport in model organic semiconductors, chosen to be solution-processable functionalized acene and anthradithiophene derivatives, is carried out. For this, various modalities of optical and photoluminescence spectroscopy are combined with measurements of charge carrier dynamics and with numerical simulations. The ultimate goal of the research is to establish the nature and properties of hybrid light-matter states in microcavities and on plasmonic nanostructured substrates and to quantify the potential of such states to enhance coherent charge transport in organic crystalline materials. More specifically, the research team seeks to establish how the properties of polaritons evolve depending on the nature of excitonic states in the organic semiconductor, molecular packing and disorder, and to lay foundations for enhancing charge carrier mobility and photocurrent in high-performance organic semiconductors via coherent hybrid states.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.