The impact of spiro-OMeTAD photodoping on the reversible light-induced transients of perovskite solar cells | ARC Centre of Excellence in Exciton Science
TitleThe impact of spiro-OMeTAD photodoping on the reversible light-induced transients of perovskite solar cells
Publication TypeJournal Article
Year of Publication2021
AuthorsTan, B, Raga, SR, Rietwyk, KJames, Lu, J, Fürer, SO, Griffith, JC, Cheng, Y-B, Bach, U
JournalNano Energy
Volume82
Pagination105658
Date Published04/2021
ISSN22112855
Abstract

Hole transporting materials (HTMs) play essential roles in facilitating hole extraction and suppressing recombination in lead halide perovskite solar cells (PSCs). High levels of p-doping in HTMs is necessary for achieving high device performance, attributed to an increased electrical conductivity. In this work, we provide evidences that the poor performance of PSCs with low levels of doping (i.e., 4 mol% spiro-OMeTAD+) in spiro-OMeTAD is mainly caused by the presence of a Schottky barrier at the perovskite/spiro-OMeTAD interface, hampering hole injection. Under continuous illumination at open-circuit condition, the barrier gradually diminishes, increasing the PSC power conversion efficiency by 70-fold after 7 h. This process is completely reversible, returning to the initial poor performance after dark storage. We attribute this improvement in performance to a gradual photodoping of spiro-OMeTAD, triggered by the transfer of photogenerated holes and mediated by the slow migration of halide anions from perovskite to compensate the newly formed spiro-OMeTAD+. In-situ parallel analyses with impedance spectroscopy (IS) and photoluminescence are employed to gain insights into the charge dynamics along with light soaking. We find that the Schottky barrier resistance overlays with the recombination signal at the high frequency arc of IS, having important implications for the IS data analysis for PSCs. The work elucidates a major mechanism causing the slow efficiency variations during light/dark cycling, commonly observed in PSCs, which complicates the determination of long-term stability.

URLhttps://www.sciencedirect.com/science/article/pii/S2211285520312313?via%3Dihub
DOI10.1016/j.nanoen.2020.105658
Short TitleNano Energy
Will this item be attributed as an output of other ARC Projects?: 
Yes
Did you acknowledge the centre in this publication?: 
Yes
Were any international co-authors involved?: 
Yes
Were any of your co-authors not affiliated with the centre?: 
Yes
Reporting year: 
2021
Impact Factor: 
Is this a joint publication between nodes?: 
No
Please list collaborating nodes: 
National collaborating institutions: 
Melbourne Centre for Nanofabrication, Australian National Fabrication Facility, CSIRO
International collaborating institutions: 
Institut Català de Nanociència i Nanotecnologia, Universitat Autònoma de Barcelona
State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology
Which Centre platforms are related to the research?: