Proceedings Article | 10 September 2019
KEYWORDS: Interfaces, Solar cells, Polymers, Modulation, Excitons, Molecular self-assembly, Perovskite, System on a chip
The performance of molecular/macromolecular and hybrid solar cells depends on understanding and controlling the interfaces between the component materials. Molecularly tailoring interfaces offers an effective and 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 electrode-active layer and active layer-active layer interfaces in almost all types of solar cells. Such interface engineering can also suppress carrier-trapping defects at interfaces and stabilize such interfaces against de-cohesion and the ingress of oxidants. For soft matter-soft matter interfaces, interfacial tailoring also enhances charge separation and photocurrent generation. In this lecture, challenges and opportunities in controlling the structures of solar cell interfaces are illustrated in the following areas:1) modulating charge transport by active layer molecular/microstructural organization,[1],[2] 2) controlling exciton splitting and carrier generation at active layer donor-acceptor interfaces,[3],[4] 3) tuning donor-acceptor combinations for maximum performance,[5],[6] 4) modulating charge transport across electrode-soft matter interfaces in polymer and perovskite cells.[7] Rational interface engineering along with improved donor and acceptor structures, guided by theoretical/computational analysis, affords large fill factors, efficiencies greater than 14%, and enhanced cell durability. All this must of course be accomplished using environmentally benign synthetic processes.[8]
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