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Optimizing the Optoelectronic Properties of Face‐On Oriented Poly(3,4‐Ethylenedioxythiophene) via Water‐Assisted Oxidative Chemical Vapor Deposition
Author(s) -
Heydari Gharahcheshmeh Meysam,
Robinson Maxwell T.,
Gleason Edward F.,
Gleason Karen K.
Publication year - 2021
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.202008712
Subject(s) - materials science , pedot:pss , crystallinity , chemical vapor deposition , conductive polymer , thin film , chemical engineering , stacking , conductivity , optoelectronics , nanotechnology , polymer , composite material , organic chemistry , chemistry , engineering
Engineering the texture and nanostructure to improve the electrical conductivity of semicrystalline conjugated polymers must address the rate‐limiting step for charge carrier transport. In highly face‐on orientation, the charge transport between chains within a crystallite becomes rate‐limiting, which is highly sensitive to the π–π stacking distance and interchain charge transfer integral. Here, face‐on oriented semicrystalline poly(3,4‐ethylenedioxythiophene) (PEDOT) thin films are grown via water‐assisted (W‐A) oxidative chemical vapor deposition (oCVD). Combining W‐A with the volatile oxidant, antimony pentachloride, yields an optimized electrical conductivity of 7520 ± 240 S cm −1 , a record for PEDOT thin films. Systematic control of π–π stacking distance from 3.50 Å down to 3.43 Å yields an electrical conductivity enhancement of ≈ 1140%. The highest electrical conductivity also corresponds to minimum in Urbach energy of 205 meV, indicating superior morphological order. The figure of merit for transparent conductors, σ dc /σ op , reaches a maximum value of 94, which is 1.9 × and 6.7 × higher than oCVD PEDOT grown without W‐A and utilizing vanadium oxytrichloride and iron chloride oxidizing agents, respectively. The W‐A oCVD is single‐step all‐dry process and provides conformal coverage, allowing direct growth on mechanical flexible, rough, and structured surfaces without the need for complex and costly transfer steps.