About

Dr. Michael Barnes is a member of the Barnes Research Group at the University of Massachusetts Amherst, within the Chemistry department. His research focuses on optical probes of chain packing structure and exciton dynamics in polythiophene films, composites, and nanostructures. His work includes probing inter- and intrachain exciton coupling in isolated poly(3-hexylthiophene) nanofibers, with particular attention to the effects of solvation and regioregularity. Dr. Barnes's contributions are reflected in publications such as articles in the Journal of Polymer Science Part B: Polymer Physics and the Journal of Physical Chemistry Letters, highlighting his expertise in the physical chemistry of conjugated polymers and nanostructured materials.

Research topics

• Chemistry
• Nanotechnology
• Organic chemistry
• Materials science
• Composite material
• Chemical engineering
• Polymer chemistry
• Computational chemistry
• Optoelectronics

Selected publications

• Wafer-scale robust graphene electronics under industrial processing conditions

  ArXiv.org · 2025-01-22 · 1 citations

  preprintOpen access

  For commercial grade electronic devices, stable structures are required to ensure a long device life span. When such devices contain nanomaterials like graphene, it is crucial that these materials resist industrial processes and harsh environments. For environments that contain water, graphene delamination is a notorious drawback, as water intercalation and eventually liftoff readily occur in aqueous and especially in alkaline solutions. This limitation renders graphene incompatible with key wafer-processing steps in the semiconductor industry. In this work, a covalent pyrene-based adhesion layer is synthesized in a facile, two-step procedure. Through π-π interactions, the adhesion of graphene to silicon wafers was maintained under conditions that resemble harsh processes, i.e. acidic and alkaline solutions, several organic solvents, and sonication. Moreover, they could be produced with a device measurement yield up to 99.7% and reproducible device-to-device electronic performance on 4-inch silicon wafers. Our results show that a straightforward functionalization of silicon wafers with an adhesive layer can be directly applicable in industrial-scale fabrication processes, giving access to robust graphene field effect devices that are built to last long.

  PublisherOA PDFDOI

• Spatial and Bidirectional Work Function Modulation of Monolayer Graphene with Patterned Polymer “Fluorozwitterists”

  ACS Central Science · 2024-08-06 · 3 citations

  articleOpen access

  diode configuration, with local increase or decrease of work function. Overall, this polymeric fluorozwitterist design is suitable for enabling simple, solution-based surface patterning and is anticipated to be useful for spatial work function modulation of 2D materials integrated into electronic devices.

  PublisherDOI

• Photonic polymer-blend structures and method for making

  OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information) · 2023-01-23

  articleOpen access1st authorCorresponding

  The present invention comprises the formation of photonic polymer-blend structures having tunable optical and mechanical properties. The photonic polymer-blend structures comprise monomer units of spherical microparticles of a polymer-blend material wherein the spherical microparticles have surfaces partially merged with one another in a robust inter-particle bond having a tunable inter-particle separation or bond length sequentially attached in a desired and programmable architecture. The photonic polymer-blend structures of the present invention can be linked by several hundred individual particles sequentially linked to form complex three-dimensional structures or highly ordered two-dimensional arrays of 3D columns with 2D spacing.

  PublisherOA PDF

• Copper Bromide Hole Transport Layer for Stable and Efficient Perovskite Solar Cells

  ACS Applied Energy Materials · 2022-07-12 · 10 citations

  article

  We demonstrate that replacing poly(3,4-ethylenedioxythiophene)-polystyrenesulfonate (PEDOT:PSS) with copper bromide (CuBr) as a hole transport layer (HTL) leads to highly efficient and stable inverted perovskite solar cells (PSCs). The CuBr-based devices showed an average power conversion efficiency (PCE) of 15.73% and a maximum PCE of 17.65%. Devices with PEDOT:PSS as the HTL had an average PCE of 10.94%. The active layer films fabricated on CuBr showed larger grain size distribution and improved crystallinity. Ultraviolet photoelectron spectroscopy and Kelvin probe force microscopy data reveal a favorable valence band alignment of CuBr with MAPbI3. We also found that CuBr-based devices exhibit a large built-in potential of 1.03 V compared to 0.77 V in PEDOT:PSS devices, which favors efficient hole extraction in the former. Compared to PEDOT:PSS, the CuBr-based PSCs also exhibited long-term stability in inert and humid environments.

  PublisherDOI

• Stabilization of Three-Particle Excitations in Monolayer MoS₂ by Fluorinated Methacrylate Polymers

  The Journal of Physical Chemistry Letters · 2022-05-25 · 3 citations

  articleSenior authorCorresponding

  While extrinsic factors, such as substrates and chemical doping, are known to strongly influence visible photoemission from monolayer MoS2, key fundamental knowledge for p-type polymeric dopants is lacking. We investigated perturbations to the electronic environment of 2D MoS2 using fluorinated polymer coatings and specifically studied stabilization of three-particle states by monitoring changes in intensities and emission maxima of three-particle and two-particle emissions. We calculated changes in carrier density and trion binding energy, the latter having an additional contribution from MoS2 polarization by the polymer. Polarization is further suggested by Kelvin probe force microscopy (KPFM) measurements of large Fermi level shifts. Changes similar in magnitude, but opposite in sign, were observed in 2D MoS2 coated with an analogous nonfluorinated polymer. These findings highlight the important interplay between electron exchange and electrostatic interactions at the interface between polymers and transition metal dichalcogenides (TMDCs), which govern fundamental electronic properties relevant to next-generation devices.

  PublisherDOI

• Electronic Tuning of Monolayer Graphene with Polymeric “Zwitterists”

  ACS Nano · 2021 · 25 citations

  • Materials science
  • Nanotechnology
  • Optoelectronics

  , "zwitterists") on monolayer graphene. Ultraviolet photoelectron spectroscopy indicated a significant work function reduction, as high as 1.5 eV, induced by all polymer zwitterions when applied as ultrathin films (<10 nm) on monolayer graphene. Of the polymers studied, the piperidinyl-substituted version, produced the largest dipole normal to the graphene sheet, thereby inducing the maximum work function reduction. Density functional theory calculations probed the influence of zwitterion composition on dipole orientation, while lithographic patterning allowed for evaluation of surface potential contrast via Kelvin probe force microscopy. Overall, this polymer "zwitterist" design holds promise for fine-tuning 2D materials electronics with spatial control based on the chemistry of the polymer coating and the dimensions of the lithographic patterning.

  PublisherDOI

• Polarization-Driven Asymmetric Electronic Response of Monolayer Graphene to Polymer Zwitterions Probed from Both Sides

  ACS Applied Materials & Interfaces · 2021-10-05 · 5 citations

  articleSenior authorCorresponding

  We investigated the nature of graphene surface doping by zwitterionic polymers and the implications of weak in-plane and strong through-plane screening using a novel sample geometry that allows direct access to either the graphene or the polymer side of a graphene/polymer interface. Using both Kelvin probe and electrostatic force microscopies, we observed a significant upshift in the Fermi level in graphene of ∼260 meV that was dominated by a change in polarizability rather than pure charge transfer with the organic overlayer. This physical picture is supported by density functional theory (DFT) calculations, which describe a redistribution of charge in graphene in response to the dipoles of the adsorbed zwitterionic moieties, analogous to a local DC Stark effect. Strong metallic-like screening of the adsorbed dipoles was observed by employing an inverted geometry, an effect identified by DFT to arise from a strongly asymmetric redistribution of charge confined to the side of graphene proximal to the zwitterion dipoles. Transport measurements confirm n-type doping with no significant impact on carrier mobility, thus demonstrating a route to desirable electronic properties in devices that combine graphene with lithographically patterned polymers.

  PublisherDOI

• Adverse Childhood Experiences Measure

  PsycTESTS Dataset · 2020-01-01

  datasetSenior author
  PublisherDOI

• Polymer Zwitterions for Stabilization of CsPbBr₃ Perovskite Nanoparticles and Nanocomposite Films

  Angewandte Chemie International Edition · 2020 · 79 citations

  • Materials science
  • Polymer chemistry
  • Chemical engineering

  perovskite nanoparticles (PNPs). These polymers produce nanocomposite films with excellent NP dispersion, optical transparency, and impressive resistance to NP degradation upon exposure to water. Multidentate interactions of the zwitterion-containing copolymers with the PNPs induce dispersed or weakly aggregated nanocomposite morphologies, depending on the extent of zwitterionic functionality in the polymer. Incorporating additional functionality into the polymers, such as benzophenone pendent groups, yields lithographically patternable films, while time-resolved photoluminescence measurements provide insight into the electronic impact of PNPs in zwitterionic polymer matrices.

  PublisherOA PDFDOI

• Counter Adverse Childhood Experiences Measure

  PsycTESTS Dataset · 2020-01-01

  datasetSenior author
  PublisherDOI

Recent grants

• Single Molecule Spectroscopy of Chiral Nanosystems: Understanding Heterogeneities in Chiroptical Interactions

  NSF · $450k · 2009–2013

Frequent coauthors

• Bobby G. Sumpter

  Center for Nanophase Materials Sciences

  60 shared

• Todd Emrick

  University of Massachusetts Amherst

  40 shared

• Adosh Mehta

  38 shared

• William B. Whitten

  Fordham University

  31 shared

• Robert M. Dickson

  Georgia Institute of Technology

  29 shared

• J. Michael Ramsey

  St George's, University of London

  29 shared

• Pradeep Kumar

  Rajalakshmi Engineering College

  26 shared

• D. W. Noid

  23 shared

Labs

• Barnes Research GroupPI