Soft Matter and Hybrid Solar Cell Interfacial Science

Molecularly tailoring interfaces with atomistic precision offers an effective, informative means to selectively modulate charge transport, molecular self-assembly, and exciton dynamics at hard matter-soft matter and soft-soft matter interfaces.  Such interfaces can act as filters to facilitate extraction of “correct charges” while blocking extraction of “incorrect charges” at the electrode-active layer and active layer-active layer interfaces in many types of solar cells.  Such interface engineering can also suppress carrier-trapping defect densities at interfaces and stabilize these interfaces against physical/thermal de-cohesion and against the ingress of oxidants.  For soft matter-soft matter interfaces, interfacial tailoring also facilitates exciton scission and photocurrent generation.  In this lecture, challenges and opportunities in solar cell interface science are illustrated for four interrelated research areas:  1) modulating charge transport across hard matter (electrode)-soft matter interfaces in polymer and perovskite solar cells, 2) controlling charge transport by specific active layer atomistic/microstructural organization in active layers and on electrodes, 3) controlling exciton dynamics and carrier generation at active layer donor-acceptor interfaces, 4) designing transparent electrodes and interfacial layers with enhanced properties.  It will be seen that rational interface engineering along with improved donor and acceptor structures, guided by theoretical/computational analysis, significantly enhances solar cell performance and durability. The symbiosis of green materials synthesis, computational modeling and simulation, materials characterization, and device fabrication and evaluation, are central.