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Title: Organofunctional Silane Modification of Aluminum-Doped Zinc Oxide Surfaces as a Route to Stabilization

Abstract

Aluminum-doped zinc oxide (AZO) is a low-temperature processed transparent conductive oxide (TCO) made of earth abundant elements; its applications are currently limited by instability to heat, moisture, and acidic conditions. We demonstrate that the application of an organofunctional silane modifier mitigates AZO degradation, and explore the interplay between performance and material composition and morphology. Specifically, we evaluate degradation of bare AZO and APTES (3-aminopropyltriethoxysilane)-modified AZO in response to damp heat (DH, 85 °C, 85 % relative humidity) exposure over 1000 h, then demonstrate how surface modification impacts changes in electrical and optical properties, and chemical composition in one of the most thorough studies to date. Hall measurements show that the resistivity of AZO increases due to a decrease in electron mobility, with no commensurate change in carrier concentration. APTES decelerates this electrical degradation, without affecting AZO optical properties. Percent transmission and yellowness index of an ensemble of bare and modified AZO are stable upon DH exposure, but haze increases slightly for a discrete sample of modified AZO. Atomic force microscopy (AFM) and optical profilometer (OP) measurements do not show evidence of pitting or delamination after 1000 h DH exposure, but indicate a slight increase in surface roughness on both themore » nanometer and micron length scales. X-ray photoelectron spectroscopy data (XPS) reveal that the surface composition of bare and silanized AZO is stable over this time frame; oxygen vacancies, as measured by XPS, are also stable with DH exposure, which, together with transmission and Hall measurements, indicate stable carrier concentrations. However, after 1500 h of DH exposure, only bare AZO shows signs of catastrophic destruction. Comparison of the data presented herein to previous reports indicates that the initial AZO composition and microstructure dictate the degradation profile. Furthermore, this work demonstrates that surface modification slows the bulk degradation of AZO, and provides insight into how the material can be more widely used as a transparent electrode in the next generation of optoelectronic devices.« less

Authors:
 [1];  [1];  [1];  [1];  [1]; ORCiD logo [1]; ORCiD logo [1]
  1. Case Western Reserve Univ., Cleveland, OH (United States)
Publication Date:
Research Org.:
Case Western Reserve Univ., Cleveland, OH (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Solar Energy Technologies Office (EE-4S)
OSTI Identifier:
1409203
Grant/Contract Number:  
EE0007360
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
ACS Applied Materials and Interfaces
Additional Journal Information:
Journal Volume: 9; Journal Issue: 20; Journal ID: ISSN 1944-8244
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; surface modification; transparent conductive oxide; aluminum-doped zinc oxide; degradation; electron mobility

Citation Formats

Matthews, Rachael, Glasser, Emily, Sprawls, Samuel C., French, Roger H., Peshek, Timothy J., Pentzer, Emily, and Martin, Ina T. Organofunctional Silane Modification of Aluminum-Doped Zinc Oxide Surfaces as a Route to Stabilization. United States: N. p., 2017. Web. doi:10.1021/acsami.7b02638.
Matthews, Rachael, Glasser, Emily, Sprawls, Samuel C., French, Roger H., Peshek, Timothy J., Pentzer, Emily, & Martin, Ina T. Organofunctional Silane Modification of Aluminum-Doped Zinc Oxide Surfaces as a Route to Stabilization. United States. doi:10.1021/acsami.7b02638.
Matthews, Rachael, Glasser, Emily, Sprawls, Samuel C., French, Roger H., Peshek, Timothy J., Pentzer, Emily, and Martin, Ina T. Mon . "Organofunctional Silane Modification of Aluminum-Doped Zinc Oxide Surfaces as a Route to Stabilization". United States. doi:10.1021/acsami.7b02638. https://www.osti.gov/servlets/purl/1409203.
@article{osti_1409203,
title = {Organofunctional Silane Modification of Aluminum-Doped Zinc Oxide Surfaces as a Route to Stabilization},
author = {Matthews, Rachael and Glasser, Emily and Sprawls, Samuel C. and French, Roger H. and Peshek, Timothy J. and Pentzer, Emily and Martin, Ina T.},
abstractNote = {Aluminum-doped zinc oxide (AZO) is a low-temperature processed transparent conductive oxide (TCO) made of earth abundant elements; its applications are currently limited by instability to heat, moisture, and acidic conditions. We demonstrate that the application of an organofunctional silane modifier mitigates AZO degradation, and explore the interplay between performance and material composition and morphology. Specifically, we evaluate degradation of bare AZO and APTES (3-aminopropyltriethoxysilane)-modified AZO in response to damp heat (DH, 85 °C, 85 % relative humidity) exposure over 1000 h, then demonstrate how surface modification impacts changes in electrical and optical properties, and chemical composition in one of the most thorough studies to date. Hall measurements show that the resistivity of AZO increases due to a decrease in electron mobility, with no commensurate change in carrier concentration. APTES decelerates this electrical degradation, without affecting AZO optical properties. Percent transmission and yellowness index of an ensemble of bare and modified AZO are stable upon DH exposure, but haze increases slightly for a discrete sample of modified AZO. Atomic force microscopy (AFM) and optical profilometer (OP) measurements do not show evidence of pitting or delamination after 1000 h DH exposure, but indicate a slight increase in surface roughness on both the nanometer and micron length scales. X-ray photoelectron spectroscopy data (XPS) reveal that the surface composition of bare and silanized AZO is stable over this time frame; oxygen vacancies, as measured by XPS, are also stable with DH exposure, which, together with transmission and Hall measurements, indicate stable carrier concentrations. However, after 1500 h of DH exposure, only bare AZO shows signs of catastrophic destruction. Comparison of the data presented herein to previous reports indicates that the initial AZO composition and microstructure dictate the degradation profile. Furthermore, this work demonstrates that surface modification slows the bulk degradation of AZO, and provides insight into how the material can be more widely used as a transparent electrode in the next generation of optoelectronic devices.},
doi = {10.1021/acsami.7b02638},
journal = {ACS Applied Materials and Interfaces},
number = 20,
volume = 9,
place = {United States},
year = {Mon May 01 00:00:00 EDT 2017},
month = {Mon May 01 00:00:00 EDT 2017}
}

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