Morphological Control of Y6 Thin Films Reveals Charge Transfer Is Facilitated by Co-facial Interactions

Abstract

The organic semiconductor Y6 has been extensively used as an acceptor in organic photovoltaic devices, yielding high efficiencies. Its unique properties include a high refractive index, intrinsic exciton dissociation, and barrierless charge generation in bulk heterojunctions. However, the direct impact of the crystal packing morphology on the photophysics of Y6 has remained elusive, hindering further development of heterojunction and homojunction devices. Herein, we study the photogenerated species in multiple distinct Y6 crystal packing geometries via transient absorption spectroscopy and photovoltaic measurements of the corresponding single-component devices. Our results reveal that “co-fa..