Dendrite growth in annealed polymer blends for use in bulk heterojunction solar cells

Abstract

This paper presents the evidence of growth of dendrites during the annealing of poly (3-hexylthiophene) and [6,6]-phenyl C61-butyric acid methyl ester (P3HT:PCBM) blends that are being explored for potential applications in bulk heterojunction polymer solar cells. These dendrites were observed in high resolution scanning electron microscopy to have morphologies that depend on the annealing temperature. Consistent with a recent eutectic phase diagram, the dendrites were not observed at 200 °C. The observations were explained by considering the effects of temperature on the kinetics of phase nucleation and growth in P3HT: PCBM blends. The implications of the results are also discussed for the stability of electrical properties in bulk heterojunction solar cells.