Tuning Organic Solar Cell Domain Properties

Despite having achieved the long sought-after performance of 10% power conversion efficiency, high performance organic solar cells are still constrained to small devices fabricated by spin coating. Efforts to scale up via printing lag considerably behind, revealing an extreme sensitivity to different fabrication methods. Here we use a lab-scale analogue to roll-to-roll printing as the fabrication tool in order to understand the impact of processing parameters on morphology and performance. 

Our studies showed that lower fabrication temperature decreased the phase separation domain size and increased the crystallinity of those domains, leading to improved photocurrent. Furthermore, we conclude that domain size in isoindigo/PCBM solar cells is dictated by spontaneous phase separation rather than crystal nucleation and growth. The deeper fundamental understanding of morphology evolution we gained will aid in the push toward scalable, high-performance devices

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