18.9% Efficient Organic Solar Cells Based on n-Doped Bulk-Heterojunction and Halogen-Substituted Self-Assembled Monolayers as Hole Extracting Interlayers
Journal article, 2022
The influence of halogen substitutions (F, Cl, Br, and I) on the energy levels of the self-assembled hole-extracting molecule [2-(9H-Carbazol-9-yl)ethyl]phosphonic acid (2PACz), is investigated. It is found that the formation of self-assembled monolayers (SAMs) of [2-(3,6-Difluoro-9H-carbazol-9-yl)ethyl]phosphonic acid (F-2PACz), [2-(3,6-Dichloro-9H-carbazol-9-yl)ethyl]phosphonic acid (Cl-2PACz), [2-(3,6-Dibromo-9H-carbazol-9-yl)ethyl]phosphonic acid (Br-2PACz), and [2-(3,6-Diiodo-9H-carbazol-9-yl)ethyl]phosphonic acid (I-2PACz) directly on indium tin oxide (ITO) increases its work function from 4.73 eV to 5.68, 5.77, 5.82, and 5.73 eV, respectively. Combining these ITO/SAM electrodes with the ternary bulk-heterojunction (BHJ) system PM6:PM7-Si:BTP-eC9 yields organic photovoltaic (OPV) cells with power conversion efficiency (PCE) in the range of 17.7%-18.5%. OPVs featuring Cl-2PACz SAMs yield the highest PCE of 18.5%, compared to cells with F-2PACz (17.7%), Br-2PACz (18.0%), or I-2PACz (18.2%). Data analysis reveals that the enhanced performance of Cl-2PACz-based OPVs relates to the increased hole mobility, decreased interface resistance, reduced carrier recombination, and longer carrier lifetime. Furthermore, OPVs featuring Cl-2PACz show enhanced stability under continuous illumination compared to ITO/PEDOT:PSS-based cells. Remarkably, the introduction of the n-dopant benzyl viologen into the BHJ further boosted the PCE of the ITO/Cl-2PACz cells to a maximum value of 18.9%, a record-breaking value for SAM-based OPVs and on par with the best-performing OPVs reported to date.
self-assembled monolayers
molecular dopants
organic solar cells
organic semiconductors
organic bulk-heterojunctions
solution processing
Author
Yuanbao Lin
King Abdullah University of Science and Technology (KAUST)
University of Oxford
Yadong Zhang
University of Colorado at Boulder
Georgia Institute of Technology
Junxiang Zhang
Georgia Institute of Technology
University of Colorado at Boulder
Mantas Marcinskas
Kaunas University of Technology
Tadas Malinauskas
Kaunas University of Technology
Artiom Magomedov
Kaunas University of Technology
Mohamad Insan Nugraha
King Abdullah University of Science and Technology (KAUST)
National Research & Innovation Agency (BRIN)
Dimitris Kaltsas
National Technical University of Athens (NTUA)
Dipti R. Naphade
King Abdullah University of Science and Technology (KAUST)
George T. Harrison
King Abdullah University of Science and Technology (KAUST)
Abdulrahman El-Labban
King Abdullah University of Science and Technology (KAUST)
Stephen Barlow
Georgia Institute of Technology
University of Colorado at Boulder
Stefaan De Wolf
King Abdullah University of Science and Technology (KAUST)
Ergang Wang
Chalmers, Chemistry and Chemical Engineering, Applied Chemistry
Iain McCulloch
King Abdullah University of Science and Technology (KAUST)
University of Oxford
Leonidas Tsetseris
National Technical University of Athens (NTUA)
Vytautas Getautis
Kaunas University of Technology
Seth R. Marder
University of Colorado at Boulder
Georgia Institute of Technology
Thomas D. Anthopoulos
King Abdullah University of Science and Technology (KAUST)
Advanced Energy Materials
1614-6832 (ISSN) 1614-6840 (eISSN)
Vol. 12 45 2202503Subject Categories
Other Chemical Engineering
Other Basic Medicine
Other Chemistry Topics
DOI
10.1002/aenm.202202503