Exploring Electronic Structure and Order in Polymers via Single-Particle Microresonator Spectroscopy
journal contributionposted on 2018-01-29, 00:00 authored by Erik H. Horak, Morgan T. Rea, Kevin D. Heylman, David Gelbwaser-Klimovsky, Semion K. Saikin, Blaise J. Thompson, Daniel D. Kohler, Kassandra A. Knapper, Wei Wei, Feng Pan, Padma Gopalan, John C. Wright, Alán Aspuru-Guzik, Randall H. Goldsmith
PEDOT:PSS, a transparent electrically conductive polymer, finds widespread use in electronic devices. While empirical efforts have increased conductivity, a detailed understanding of the coupled electronic and morphological landscapes in PEDOT:PSS has lagged due to substantial structural heterogeneity on multiple length-scales. We use an optical microresonator-based absorption spectrometer to perform single-particle measurements, providing a bottom-up examination of electronic structure and morphology ranging from single PEDOT:PSS polymers to nascent films. Using single-particle spectroscopy with complementary theoretical calculations and ultrafast spectroscopy, we demonstrate that PEDOT:PSS displays bulk-like optical response even in single polymers. We find highly ordered PEDOT assemblies with long-range ordering mediated by the insulating PSS matrix and reveal a preferential surface orientation of PEDOT nanocrystallites absent in bulk films with implications for interfacial electronic communication. Our single-particle perspective provides a unique window into the microscopic structure and electronic properties of PEDOT:PSS.