@article{77eb6976db574a8ca75386fae7a8b874,
title = "A Chemically Orthogonal Hole Transport Layer for Efficient Colloidal Quantum Dot Solar Cells",
abstract = "Colloidal quantum dots (CQDs) are of interest in light of their solution-processing and bandgap tuning. Advances in the performance of CQD optoelectronic devices require fine control over the properties of each layer in the device materials stack. This is particularly challenging in the present best CQD solar cells, since these employ a p-type hole-transport layer (HTL) implemented using 1,2-ethanedithiol (EDT) ligand exchange on top of the CQD active layer. It is established that the high reactivity of EDT causes a severe chemical modification to the active layer that deteriorates charge extraction. By combining elemental mapping with the spatial charge collection efficiency in CQD solar cells, the key materials interface dominating the subpar performance of prior CQD PV devices is demonstrated. This motivates to develop a chemically orthogonal HTL that consists of malonic-acid-crosslinked CQDs. The new crosslinking strategy preserves the surface chemistry of the active layer beneath, and at the same time provides the needed efficient charge extraction. The new HTL enables a 1.4× increase in charge carrier diffusion length in the active layer; and as a result leads to an improvement in power conversion efficiency to 13.0% compared to EDT standard cells (12.2%).",
keywords = "chemical orthogonality, colloidal quantum dots, hole transport layers, solar cells, surface ligands",
author = "Margherita Biondi and Choi, {Min Jae} and Olivier Ouellette and Baek, {Se Woong} and Petar Todorovi{\'c} and Bin Sun and Seungjin Lee and Mingyang Wei and Peicheng Li and Kirmani, {Ahmad R.} and Sagar, {Laxmi K.} and Richter, {Lee J.} and Sjoerd Hoogland and Lu, {Zheng Hong} and {Garc{\'i}a de Arquer}, {F. Pelayo} and Sargent, {Edward H.}",
note = "Funding Information: M.B. and M.‐J.C. contributed equally to this work. This work was supported by Ontario Research Fund‐Research Excellence program (ORF7‐Ministry of Research and Innovation, Ontario Research Fund‐Research Excellence Round 7), and by the Natural Sciences and Engineering Research Council (NSERC) of Canada. This research used resources of the National Synchrotron Light Source II, which are U.S. DOE Office of Science Facilities, at Brookhaven National Laboratory under contract no. DE‐SC0012704. The authors acknowledge the financial support from QD Solar Inc. The authors thank D. Kopilovic, E. Palmiano, L. Levina, and R. Wolowiec for the technical support. Funding Information: M.B. and M.-J.C. contributed equally to this work. This work was supported by Ontario Research Fund-Research Excellence program (ORF7-Ministry of Research and Innovation, Ontario Research Fund-Research Excellence Round 7), and by the Natural Sciences and Engineering Research Council (NSERC) of Canada. This research used resources of the National Synchrotron Light Source II, which are U.S. DOE Office of Science Facilities, at Brookhaven National Laboratory under contract no. DE-SC0012704. The authors acknowledge the financial support from QD Solar Inc. The authors thank D. Kopilovic, E. Palmiano, L. Levina, and R. Wolowiec for the technical support. Publisher Copyright: {\textcopyright} 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim",
year = "2020",
month = apr,
day = "1",
doi = "10.1002/adma.201906199",
language = "English (US)",
volume = "32",
journal = "Advanced Materials",
issn = "0935-9648",
publisher = "Wiley-VCH Verlag",
number = "17",
}