Nanomorphology of polythiophene-fullerene bulk-heterojunction films investigated by structured illumination optical imaging and time-resolved confocal microscopy

• Published in: Methods and applications in fluorescence Vol. 1; no. 1; p. 015004
• Main Authors: Hao, X-T, Hirvonen, L M, Smith, T A
• Format: Journal Article
• Language: English
• Published: England 28.01.2013
• ISSN: 2050-6120
• DOI: 10.1088/2050-6120/1/1/015004

Structured illumination microscopy (SIM) and time-resolved confocal fluorescence microscopy are applied to investigate the nanomorphology of thin films comprising typical blends of the conjugated polymer, poly (3-hexylthiophene) (P3HT), and [6, 6]-phenyl C -butyric acid methyl ester (PCBM), used for organic photovoltaic applications. SIM provides evidence for the presence of a thin emissive region around the crystalline regions of PCBM and at the tips of rod-like domains. The time-resolved measurements show that the emission surrounding the PCBM rods is longer lived than the bulk of the film. The two modes of microscopy provide complementary evidence indicating that electron-hole separation is inhibited between the polymer and the large PCBM-rich domains in these regions. We show here that structured illumination microscopy is a viable method of gaining additional information from these photovoltaic materials, despite their weak emission.