Achievement

Polymer solar cells with a high efficiency inverted structure were fabricated by low temperature annealing of an interlayer comprised of Cs2CO3. The improved device performance was attributed to the lower interfacial resistance the vertical phase separation. Vertical phase separation in the polymer-fullerene system was revealed by delaminating the polymer films using water to investigate the bottom interface. XPS AFM studies showed donor fullerene-enrichment at the air bottom interfaces, respectively. This vertically inhomogeneous distribution of material can be controlled by varying the substrate surface properties significantly affects the device performance making the inverted structure a promising alternative to traditional polymer solar cells. In an interdisciplinary project between the groups of Professors Kaner Yang a low temperature solution-processed graphene-CNT hybrid material was fabricated electrode applications for polymer based solar cells demonstrated.