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Mitigating Detrimental Effect of Self‐Doping Near the Anode in Highly Efficient Organic Solar Cells

Yong Kim, Oskar Sandberg Orcid Logo, Stefan Zeiske, Gregory Burwell Orcid Logo, Drew Riley, Paul Meredith Orcid Logo, Ardalan Armin Orcid Logo

Advanced Functional Materials, Volume: 33, Issue: 16

Swansea University Authors: Yong Kim, Oskar Sandberg Orcid Logo, Stefan Zeiske, Gregory Burwell Orcid Logo, Drew Riley, Paul Meredith Orcid Logo, Ardalan Armin Orcid Logo

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DOI (Published version): 10.1002/adfm.202300147

Abstract

Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) has been one of the most established hole transport layers (HTL) in organic solar cells (OSCs) for several decades. However, the presence of PSS− ions is known to deteriorate device performance via a number of mechanisms including di...

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Published in: Advanced Functional Materials
ISSN: 1616-301X 1616-3028
Published: Wiley 2023
Online Access: Check full text

URI: https://cronfa.swan.ac.uk/Record/cronfa63787
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Abstract: Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) has been one of the most established hole transport layers (HTL) in organic solar cells (OSCs) for several decades. However, the presence of PSS− ions is known to deteriorate device performance via a number of mechanisms including diffusion to the HTL-active layer interface and unwanted local chemical reactions. In this study, it is shown that PSS− ions can also result in local p-doping in the high efficiency donor:non-fullerene acceptor blends – resulting in photocurrent loss. To address these issues, a facile and effective approach is reported to improve the OSC performance through a two-component hole transport layer (HTL) consisting of a self-assembled monolayer of 2PACz ([2-(9H-Carbazol-9-yl)ethyl]phosphonic acid) and PEDOT:PSS. The power conversion efficiency (PCE) of 17.1% using devices with PEDOT:PSS HTL improved to 17.7% when the PEDOT:PSS/2PACz two-component HTL is used. The improved performance is attributed to the overlaid 2PACz layer preventing the formation of an intermixed p-doped PSS− ion rich region (≈5–10 nm) at the bulk heterojunction-HTL contact interface, resulting in decreased recombination losses and improved stability. Moreover, the 2PACz monolayer is also found to reduce electrical shunts that ultimately yield improved performance in large area devices with PCE enhanced from 12.3% to 13.3% in 1 cm2 cells.
Keywords: Self-doping, anode, organic solar cells
College: Faculty of Science and Engineering
Funders: This work was supported by the Welsh Government's Sêr Cymru II Program through the European Regional Development Fund, Welsh European Funding Office, and Swansea University strategic initiative in Sustainable Advanced Materials. A.A. is a Sêr Cymru II Rising Star Fellow and P.M. is a Sêr Cymru II National Research Chair. This work was also funded by UKRI through the EPSRC Program Grant EP/T028511/1 Application Targeted Integrated Photovoltaics. Swansea University.
Issue: 16