Exploring Electronic Structure and Order in Polymers via Single-Particle Microresonator Spectroscopy

Abstract

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.

Whispering-Gallery Sensors

“…One is WGM resonator-based absorption spectrometry, whereby a pump laser is used to heat the nanoparticles and the dissipated heat is sensed by monitoring the WGM resonance shift using a probe laser. 79 , 80 , 81 , 82 The signal is based on optical absorption, making this technique especially suited for studying nanoparticles made of absorbing materials such as gold and conjugated polymers. Another indirect technique is based on the optomechanical coupling between optical WGM resonances and long-range phonons, enabling the measurement of particle mass density, mechanical compressibility, and viscoelasticity.…”

WrightTools: a Python package for multidimensional spectroscopy

“…WrightTools has directly enabled no fewer than eleven publications (Chen et al, 2017;Czech et al, 2015;Horak et al, 2018;Kohler, Thompson, & Wright, 2017Morrow, Kohler, & Wright, 2017;Morrow, Kohler, Czech, & Wright, 2018;Neff-Mallon & Wright, 2017;. Many of these publications have associated open datasets and WrightTools-based processing scripts which enhance the scientific community's ability to audit and reproduce the published work.…”

Toward Real-Time Monitoring and Control of Single Nanoparticle Properties with a Microbubble Resonator Spectrometer

“…12 However, the ability to perform spectroscopy on adsorbed objects would not only open a path toward label-free chemical identification, but also allow the interrogation of single object properties, free from the static and dynamic blurring of typical ensemble measurements. To this end, we recently employed microtoroid resonators as single-particle absorption spectrometers, whereby the heat dissipated by optically pumped nano-objects such as gold nanorods (AuNRs), [13][14][15][16] carbon nanotubes, 17 or conductive polymers 18 is detected via small shifts in the WGM resonance condition. However, to harness the sensitivity of this method for chemically dynamic systems, a platform easily compatible with solution-phase measurements is necessary.…”