Photophysics, Photochemistry and Optoelectronics of Singlet Fission Organic Materials in Microcavities

Organic (opto)electronic materials have been explored in a variety of applications in electronics and photonics, driven by several advantages over traditional silicon technology, including low-cost processing, fabrication of large-area flexible devices, and widely tunable properties through functionalization of the molecules. Over the past decade, remarkable progress has been achieved in understanding physical mechanisms and in developing guidelines for the material design, which boosted the performance of organic devices that rely on photophysics and/or (photo)conductive properties of the material. However, further improvements in device performance are desirable, and challenges related to (photo)stability of organic devices need addressing.<br/>One of the major thrusts in developing new organic materials and device concepts has focused on materials exhibiting singlet fission, which is a carrier multiplication process which would enable, for example, enhanced power conversion efficiencies in solar cells. Nevertheless, fundamental questions pertaining to exciton physics in singlet fission materials, and how it can be manipulated by material design and external parameters, remain. Some of these questions will be addressed in this presentation using model singlet fission organic materials, exemplified by functionalized acene and anthradithiophene derivatives, and combinations of photoluminescence and ultrafast transient absorption time-resolved spectroscopy carried out in a broad range of temperatures and magnetic fields.<br/>Strong exciton-photon coupling that occurs when an organic film is placed in a microcavity, enabling formation of a light-matter hybrid state (polariton), presents a largely unexplored opportunity to control photophysics, photochemistry, and optoelectronic characteristics in existing singlet fission materials and devices by using polaritons. This presentation will summarize our efforts aiming to understand and tune exciton polariton properties in model singlet fission organic materials, towards exploiting these properties in optoelectronic devices and controlling photochemical reactions directly relevant to photostability.