Molecular Doping of the Hole-Transporting Layer for Efficient, Single-Step Deposited Colloidal Quantum Dot Photovoltaics

Ahmad R. Kirmani, F. Pelayo Garcia de Arquer, James Z. Fan, Jafar Iqbal Khan, Grant Walters, Sjoerd Hoogland, Nimer Wehbe, Marcel M. Said, Stephen Barlow, Frédéric Laquai, Seth R. Marder, Edward H. Sargent, Aram Amassian

Research output: Contribution to journalArticlepeer-review

35 Scopus citations

Abstract

Employment of thin perovskite shells and metal halides as surface-passivants for colloidal quantum dots (CQDs) have been important, recent developments in CQD optoelectronics. These have opened the route to single-step deposited high-performing CQD solar cells. These promising architectures employ a QD hole-transporting layer (HTL) whose intrinsically shallow Fermi level (EF) restricts band-bending at maximum power-point during solar cell operation limiting charge collection. Here, we demonstrate a generalized approach to effectively balance band-edge energy levels of the main CQD absorber and charge-transport layer for these high-performance solar cells. Briefly soaking the QD HTL in a solution of the metal-organic p-dopant, molybdenum tris(1-(trifluoroacetyl)-2-(trifluoromethyl)ethane-1,2-dithiolene), effectively deepens its Fermi level, resulting in enhanced band bending at the HTL:absorber junction. This blocks the back-flow of photo-generated electrons, leading to enhanced photocurrent and fill factor compared to undoped devices. We demonstrate 9.0% perovskite-shelled and 9.5% metal-halide-passivated CQD solar cells, both achieving ca. 10% relative enhancements over undoped baselines.
Original languageEnglish (US)
Pages (from-to)1952-1959
Number of pages8
JournalACS Energy Letters
Volume2
Issue number9
DOIs
StatePublished - Aug 8 2017

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