Role of Interfacial Interactions in the Graphene-Directed Assembly of Monolayer Conjugated Polymers

Prapti Kafle, Siyuan Huang, Kyung Sun Park, Fengjiao Zhang, Hao Yu, Caroline E. Kasprzak, Hyunchul Kim, Charles M. Schroeder, Arend M. Van Der Zande, Ying Diao

Research output: Contribution to journalArticlepeer-review

Abstract

Development of graphene-organic hybrid electronics is one of the most promising directions for next-generation electronic materials. However, it remains challenging to understand the graphene-organic semiconductor interactions right at the interface, which is key to designing hybrid electronics. Herein, we study the influence of graphene on the multiscale morphology of solution-processed monolayers of conjugated polymers (PII-2T, DPP-BTz, DPP2T-TT, and DPP-T-TMS). The strong interaction between graphene and PII-2T was manifested in the high fiber density and high film coverage of monolayer films deposited on graphene compared to plasma SiO2substrates. The monolayer films on graphene also exhibited a higher relative degree of crystallinity and dichroic ratio or polymer alignment, i.e., higher degree of order. Raman spectroscopy revealed the increased backbone planarity of the conjugated polymers upon deposition on graphene as well as the existence of electronic interaction across the interface. This speculation was further substantiated by the results of photoelectron spectroscopy (XPS and UPS) of PII-2T, which showed a decrease in binding energy of several atomic energy levels, movement of the Fermi level toward HOMO, and an increase in work function, all of which indicate p-doping of the polymer. Our results provide a new level of understanding on graphene-polymer interactions at nanoscopic interfaces and the consequent impact on multiscale morphology, which will aid in the design of efficient graphene-organic hybrid electronics.

Original languageEnglish (US)
Pages (from-to)6984-6995
Number of pages12
JournalLangmuir
Volume38
Issue number22
DOIs
StatePublished - Jun 7 2022

ASJC Scopus subject areas

  • Condensed Matter Physics
  • General Materials Science
  • Spectroscopy
  • Surfaces and Interfaces
  • Electrochemistry

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