Effects of Alkyl Spacer Length in Carbazole-Based Self-Assembled Monolayer Materials on Molecular Conformation and Organic Solar Cell Performance
Journal article, 2025
Carbazole-based self-assembled monolayer (SAM) materials as hole transport layers (HTL) have led organic solar cells (OSCs) to state-of-the-art photovoltaic performance. Nonetheless, the impact of the alkyl spacer length of SAMs remains inadequately understood. To improve the knowledge, four dichloride-substituted carbazole-based SAMs (from 2Cl-2PACz to 2Cl-5PACz) with spacer lengths of 2–5 carbon atoms is developed. Single crystal analyses reveal that SAMs with shorter spacers exhibit stronger intermolecular interactions and denser packing. The molecular conformation of SAMs significantly impacts their molecular footprint and coverage on ITO. These factors result in the highest coverage of 2Cl-2PACz and the lowest coverage for 2Cl-3PACz on ITO. OSCs based on PM6:L8-BO with 2Cl-2PACz as HTL achieved high efficiencies of 18.95% and 18.62% with and without methanol rinsing of the ITO/SAMs anodes, corresponding to monolayer and multilayer structures, respectively. In contrast, OSCs utilizing the other SAMs showed decreased efficiencies as spacer length increased. The superior performance of 2Cl-2PACz can be attributed to its shorter spacer, which reduces series resistance, hole tunneling distance, and barrier. This work provides valuable insights into the design of SAMs for high-performance OSCs.
self-assembled monolayer (SAM)
alkyl spacer length
intermolecular interaction
molecular conformation
single crystals
Author
Qiaonan Chen
Chalmers, Chemistry and Chemical Engineering, Applied Chemistry
Kangbo Sun
Shenzhen Technology University
Leandro R. Franco
Karlstad University
Jingnan Wu
Chalmers, Chemistry and Chemical Engineering, Applied Chemistry
Lars Öhrström
Chalmers, Chemistry and Chemical Engineering, Chemistry and Biochemistry
X. J. Liu
Linköping University
Maureen Gumbo
Chalmers, Chemistry and Chemical Engineering, Chemistry and Biochemistry
Mailde S. Ozório
University of Copenhagen
C. Moyses Araujo
Uppsala University
Karlstad University
Guangye Zhang
Shenzhen Technology University
Karlstad University
André Johansson
Karlstad University
Ellen Moons
Karlstad University
M. Fahlman
Linköping University
Donghong Yu
Aalborg University
Sino-Danish Center for Education and Research Denmark
Yufei Wang
Shenzhen Technology University
Ergang Wang
Zhengzhou University
Chalmers, Chemistry and Chemical Engineering, Applied Chemistry
Advanced Science
2198-3844 (ISSN) 21983844 (eISSN)
Vol. 12 4 2410277Biodegradable semiconducting polymers for transient electronics
Formas (2023-01008), 2024-01-01 -- 2026-12-31.
Alkyl chain linked conjugated polymers for stable polymer solar cells
Swedish Research Council (VR) (2019-04683), 2020-01-01 -- 2023-12-31.
Areas of Advance
Nanoscience and Nanotechnology
Subject Categories (SSIF 2011)
Energy Engineering
Infrastructure
Chalmers Materials Analysis Laboratory
DOI
10.1002/advs.202410277
PubMed
39629953