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ORaCEL Seminar – Brian Collins
June 14, 2019 | 11:00 am - 12:00 pm
Title: Quantifying Effects of Molecular Interfaces on Device Dynamics via Resonant Soft X-Rays
Abstract: With printable single-junction organic solar cell efficiencies reaching 16%, the economic viability of a >20% efficient, printable, and non-toxic panel is more achievable than ever before. To realize such a device near its limiting performance, however, a much more quantitative and granular model of how molecular ordering affects charge generation is required. The development of resonant soft X-ray scattering (RSoXS) has considerably aided nanostructure characterization yet is still rather undeveloped. I will discuss using new analytical models of RSoXS going beyond the simplistic 2-phase assumptions and that quantify the device donor-acceptor interfaces toward characterizing interfacial molecular orientation. We have, furthermore, developed an in-situ photophysical measurement suite, including time-delayed collection field. This suite and new device analysis quantifies the full excited state population dynamics on the exact same devices within which we measure the nanostructure. This has resulted in unprecedentedly quantitative structure-property relationships in model systems that reveal the effect of the mixed amorphous interface. With this new capability, functional relationships that dictate device performance from interfacial aggregation, mixing, and molecular orientation can be used to tailor molecular architecture and device processing that achieves the promise of truly competitive large scale solar harvesting.