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Title: Thermally Stable Perovskite Solar Cells by Systematic Molecular Design of the Hole-Transport Layer

Abstract

With the burgeoning performance of metal halide perovskite solar cells (PSC), one of the biggest challenges to date is addressing device stability. Within the PSC device stack, charge-selective contact selection has been shown to considerably impact PSC stability. Recently, a triarylamine-based hole-transport layer (HTL) doped with its oxidized organic salt analogue (EH44/EH44-ox) has been shown to bypass the need for hygroscopic lithium salt dopants, enabling high PSC stability in ambient conditions. Despite these promising results, the improved stability came with a power conversion efficiency (PCE) penalty and poor performance above 30 degrees C. Broadening the applicability and understanding of this under-utilized dopant system, we report design criteria for stable, synthetically simple triarylamine-based organic hole transport materials (HTM) and their corresponding oxidized salts as HTL dopants for improved PSC efficiency and stability at elevated temperature. The triarylamine-based dopants must contain at least two para-electron donating groups for radical cation stabilization to prevent impurity formation (e.g., dopant reduction) which significantly reduces PSC fill factors (FF) and PCE. To further improve PSC FF and PCE, these dopants can be interchanged with respect to the HTL matrix. The stability of unencapsulated devices prepared with these three new HTLs, under constant load and illumination, considerablymore » outperform both EH44/EH44-ox and Li+-doped spiro-OMeTAD controls at 50 degrees C. The ability to mix and match a stable dopant with a non-identical small-molecule-based HTL matrix for improved charge-transport properties broadens design scope for highly stable and cost-effective PSC without sacrificing performance.« less

Authors:
ORCiD logo [1];  [2]; ORCiD logo [3];  [4];  [5]; ORCiD logo [6]; ORCiD logo [7];  [7]; ORCiD logo [7]; ORCiD logo [2]
  1. Colorado School of Mines, Golden, CO (United States)
  2. National Renewable Energy Lab. (NREL), Golden, CO (United States); Colorado School of Mines, Golden, CO (United States)
  3. National Renewable Energy Lab. (NREL), Golden, CO (United States); Hope College, Holland, MI (United States)
  4. Univ. of Denver, CO (United States)
  5. Univ. of Colorado, Boulder, CO (United States); Univ. of Nova Gorica, Vipavska (Republic of Slovenia)
  6. National Renewable Energy Lab. (NREL), Golden, CO (United States); Northwestern Polytechnical Univ., Xi'an (China)
  7. National Renewable Energy Lab. (NREL), Golden, CO (United States)
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Renewable Power Office. Solar Energy Technologies Office
OSTI Identifier:
1491373
Report Number(s):
NREL/JA-5900-71921
Journal ID: ISSN 2380-8195
Grant/Contract Number:  
AC36-08GO28308
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
ACS Energy Letters
Additional Journal Information:
Journal Volume: 4; Journal Issue: 2; Journal ID: ISSN 2380-8195
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 36 MATERIALS SCIENCE; perovskite solar cells; metal halide; stability; hole transport material

Citation Formats

Schloemer, Tracy H., Gehan, Timothy S., Christians, Jeffrey A., Mitchell, Deborah G., Dixon, Alex, Li, Zhen, Zhu, Kai, Berry, Joseph J., Luther, Joseph M., and Sellinger, Alan. Thermally Stable Perovskite Solar Cells by Systematic Molecular Design of the Hole-Transport Layer. United States: N. p., 2019. Web. doi:10.1021/acsenergylett.8b02431.
Schloemer, Tracy H., Gehan, Timothy S., Christians, Jeffrey A., Mitchell, Deborah G., Dixon, Alex, Li, Zhen, Zhu, Kai, Berry, Joseph J., Luther, Joseph M., & Sellinger, Alan. Thermally Stable Perovskite Solar Cells by Systematic Molecular Design of the Hole-Transport Layer. United States. https://doi.org/10.1021/acsenergylett.8b02431
Schloemer, Tracy H., Gehan, Timothy S., Christians, Jeffrey A., Mitchell, Deborah G., Dixon, Alex, Li, Zhen, Zhu, Kai, Berry, Joseph J., Luther, Joseph M., and Sellinger, Alan. Tue . "Thermally Stable Perovskite Solar Cells by Systematic Molecular Design of the Hole-Transport Layer". United States. https://doi.org/10.1021/acsenergylett.8b02431. https://www.osti.gov/servlets/purl/1491373.
@article{osti_1491373,
title = {Thermally Stable Perovskite Solar Cells by Systematic Molecular Design of the Hole-Transport Layer},
author = {Schloemer, Tracy H. and Gehan, Timothy S. and Christians, Jeffrey A. and Mitchell, Deborah G. and Dixon, Alex and Li, Zhen and Zhu, Kai and Berry, Joseph J. and Luther, Joseph M. and Sellinger, Alan},
abstractNote = {With the burgeoning performance of metal halide perovskite solar cells (PSC), one of the biggest challenges to date is addressing device stability. Within the PSC device stack, charge-selective contact selection has been shown to considerably impact PSC stability. Recently, a triarylamine-based hole-transport layer (HTL) doped with its oxidized organic salt analogue (EH44/EH44-ox) has been shown to bypass the need for hygroscopic lithium salt dopants, enabling high PSC stability in ambient conditions. Despite these promising results, the improved stability came with a power conversion efficiency (PCE) penalty and poor performance above 30 degrees C. Broadening the applicability and understanding of this under-utilized dopant system, we report design criteria for stable, synthetically simple triarylamine-based organic hole transport materials (HTM) and their corresponding oxidized salts as HTL dopants for improved PSC efficiency and stability at elevated temperature. The triarylamine-based dopants must contain at least two para-electron donating groups for radical cation stabilization to prevent impurity formation (e.g., dopant reduction) which significantly reduces PSC fill factors (FF) and PCE. To further improve PSC FF and PCE, these dopants can be interchanged with respect to the HTL matrix. The stability of unencapsulated devices prepared with these three new HTLs, under constant load and illumination, considerably outperform both EH44/EH44-ox and Li+-doped spiro-OMeTAD controls at 50 degrees C. The ability to mix and match a stable dopant with a non-identical small-molecule-based HTL matrix for improved charge-transport properties broadens design scope for highly stable and cost-effective PSC without sacrificing performance.},
doi = {10.1021/acsenergylett.8b02431},
url = {https://www.osti.gov/biblio/1491373}, journal = {ACS Energy Letters},
issn = {2380-8195},
number = 2,
volume = 4,
place = {United States},
year = {2019},
month = {1}
}

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