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Title: High work-function hole transport layers by self-assembly using a fluorinated additive

Abstract

The hole transport polymer poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) derives many of its favorable properties from a PSS-rich interfacial layer that forms spontaneously during coating. Since PEDOT:PSS is only usable as a blend it is not possible to study PEDOT:PSS without this interfacial layer. Through the use of the self-doped polymer sulfonated poly(thiophene-3-[2-(2-methoxyethoxy) ethoxy]-2,5-diyl) (S-P3MEET) and a polyfluorinated ionomer (PFI) it is possible to compare transparent conducting organic films with and without interfacial layers and to understand their function. Using neutron reflectometry, we show that PFI preferentially segregates at the top surface of the film during coating and forms a thermally stable surface layer. Because of this distribution we find that even small amounts of PFI increase the electron work function of the HTL. We also find that annealing at 150°C and above reduces the work function compared to samples heated at lower temperatures. Using near edge x-ray absorption fine structure spectroscopy and gas chromatography we show that this reduction in work function is due to S-P3MEET being doped by PFI. Organic photovoltaic devices with S-P3MEET/PFI hole transport layers yield higher power conversion efficiency than devices with pure S-P3MEET or PEDOT:PSS hole transport layers. Additionally, devices with a doped interface layer of S-P3MEET/PFImore » show superior performance to those with un-doped S-P3MEET.« less

Authors:
 [1];  [1];  [2];  [1];  [3];  [4];  [4];  [1]
  1. Univ. of California, Davis, CA (United States). Dept. of Chemical Engineering and Materials Science
  2. Duzce Univ. (Turkey). Dept. of Physics
  3. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  4. Univ. of California, Davis, CA (United States). Dept. of Chemistry
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1376021
Report Number(s):
LLNL-JRNL-637759
Journal ID: ISSN 2050-7526; JMCCCX
Grant/Contract Number:  
AC52-07NA27344; AC52-06NA25396; FG36-08GO18018
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Materials Chemistry. C
Additional Journal Information:
Journal Volume: 2; Journal Issue: 1; Journal ID: ISSN 2050-7526
Publisher:
Royal Society of Chemistry
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 14 SOLAR ENERGY

Citation Formats

Mauger, Scott A., Li, Jun, Özmen, Özge Tüzün, Yang, Andy Y., Friedrich, Stephan, Rail, M. Diego, Berben, Louise A., and Moulé, Adam J.. High work-function hole transport layers by self-assembly using a fluorinated additive. United States: N. p., 2013. Web. doi:10.1039/C3TC30973H.
Mauger, Scott A., Li, Jun, Özmen, Özge Tüzün, Yang, Andy Y., Friedrich, Stephan, Rail, M. Diego, Berben, Louise A., & Moulé, Adam J.. High work-function hole transport layers by self-assembly using a fluorinated additive. United States. doi:10.1039/C3TC30973H.
Mauger, Scott A., Li, Jun, Özmen, Özge Tüzün, Yang, Andy Y., Friedrich, Stephan, Rail, M. Diego, Berben, Louise A., and Moulé, Adam J.. Wed . "High work-function hole transport layers by self-assembly using a fluorinated additive". United States. doi:10.1039/C3TC30973H. https://www.osti.gov/servlets/purl/1376021.
@article{osti_1376021,
title = {High work-function hole transport layers by self-assembly using a fluorinated additive},
author = {Mauger, Scott A. and Li, Jun and Özmen, Özge Tüzün and Yang, Andy Y. and Friedrich, Stephan and Rail, M. Diego and Berben, Louise A. and Moulé, Adam J.},
abstractNote = {The hole transport polymer poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) derives many of its favorable properties from a PSS-rich interfacial layer that forms spontaneously during coating. Since PEDOT:PSS is only usable as a blend it is not possible to study PEDOT:PSS without this interfacial layer. Through the use of the self-doped polymer sulfonated poly(thiophene-3-[2-(2-methoxyethoxy) ethoxy]-2,5-diyl) (S-P3MEET) and a polyfluorinated ionomer (PFI) it is possible to compare transparent conducting organic films with and without interfacial layers and to understand their function. Using neutron reflectometry, we show that PFI preferentially segregates at the top surface of the film during coating and forms a thermally stable surface layer. Because of this distribution we find that even small amounts of PFI increase the electron work function of the HTL. We also find that annealing at 150°C and above reduces the work function compared to samples heated at lower temperatures. Using near edge x-ray absorption fine structure spectroscopy and gas chromatography we show that this reduction in work function is due to S-P3MEET being doped by PFI. Organic photovoltaic devices with S-P3MEET/PFI hole transport layers yield higher power conversion efficiency than devices with pure S-P3MEET or PEDOT:PSS hole transport layers. Additionally, devices with a doped interface layer of S-P3MEET/PFI show superior performance to those with un-doped S-P3MEET.},
doi = {10.1039/C3TC30973H},
journal = {Journal of Materials Chemistry. C},
number = 1,
volume = 2,
place = {United States},
year = {Wed Oct 30 00:00:00 EDT 2013},
month = {Wed Oct 30 00:00:00 EDT 2013}
}

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