The ability to fabricate molecularly tailored interfaces with nanoscale precision offers means to selectively modulate charge transport, molecular assembly, and exciton dynamics at hard matter-soft matter and soft-soft matter interfaces. Such interfaces can facilitate transport of the “correct charges” while blocking transport of the “incorrect charges” at the electrode-active layer interfaces of organic photovoltaic cells. This interfacial tailoring can also suppress carrier-trapping defect densities at interfaces and stabilize them with respect to physical/thermal de-cohesion. For soft matter-soft matter interfaces, interfacial tailoring can also facilitate exciton scission and photocurrent generation in such cells. In this lecture, challenges and opportunities in organic photovoltaic interface science are illustrated for four specific and interrelated areas of research: 1) controlling charge transport across hard matter(electrode)-soft matter interfaces in organic photovoltaic cells, 2) controlling charge transport by specific active layer nano/microstructural organization in the bulk active material and at the electrodes, 3) controlling exciton dynamics and carrier generation at donor-acceptor interfaces in the active layer, 4) designing transparent conducting electrodes with improved properties. It will be seen that such rational interface engineering along with improved bulk-heterojunction polymer structures guided by theoretical/computational analysis affords exceptional fill factors, solar power conversion efficiencies greater than 9%, and enhanced cell durability. The symbiosis of materials synthesis, computational modeling and simulation, materials characterization, and device fabrication and evaluation, are central to the success of this effort.

Interface science of soft matter and hybrid photovoltaics

251st National Meeting (2016)

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