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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 40: Hybrid, Organic and Perovskite Optoelectronics and Photovoltaics IV
CPP 40.2: Vortrag
Mittwoch, 11. März 2026, 17:15–17:30, ZEU/LICH
Limiting factors to free charge generation in low-bandgap organic blends for photovoltaic applications and beyond — •Manasi Pranav1, Atul Shukla1,2, and Dieter Neher1 — 1University of Potsdam, Potsdam, Germany — 2University of Queensland, Brisbane, Australia
Despite possessing similar theoretical limits, state-of-the-art organic solar cells outshine low-bandgap organic blends (absorption edge beyond 1000 nm) in their exciton harvesting efficiency. An understanding of these free charge generation mechanisms is needed to tap into the potential of such low-bandgap non-fullerene acceptors (NFAs) for photovoltaic and photodetector applications. To this end, we probe the pathways of exciton dissociation and charge-transfer state separation in multiple D:NFA systems with varying absorption edges, and varying extents of energy-transfer or charge-transfer prior to free charge generation. This is done by combining transient and steady-state optoelectronic techniques, to resolve the losses incurred between photon absorption and carrier extraction. For some of these systems, namely in blends using Y6 derivatives with extended pi-conjugation, we find that the kinetic competition between geminate charge-transfer state decay and its separation is a major limiting role in the overall photon harvesting capability of the devices. As part of ongoing work, these investigations aim to reveal the underlying geminate loss pathways, which limit overall internal quantum efficiency of the blends and, in turn, limit the figures of merit of the resulting devices.
Keywords: free charge generation; organic solar cells; organic photodetectors; low-bandgap materials; geminate loss pathways