Layered Defect-Filling co-Assembled Carbazole-Based SAMs Deliver 20% Organic Solar Cells and 17% Mini-Modules
Journal article, 2027
Self-assembled monolayers (SAMs) are widely used as hole-transport layers (HTLs) in organic solar cells (OSCs), yet conventional single-component SAMs often form quasi-monolayers with incomplete coverage and interfacial defects that become increasingly detrimental upon device scaling. Here, we develop a co-assembled multilayered SAM (coSAMu) strategy that combines two SAM molecules, 2PACz and 2Cl-4PACz, with distinct dipoles and steric configurations through blend casting and sequential casting. Photoelectron spectroscopy, X-ray analysis, and molecular simulations support a layered structure in which a chemisorbed, 2PACz-rich bottom layer primarily sets the indium tin oxide (ITO) work function, while a 2Cl-4PACz-rich upper layer fills interfacial voids, improves molecular packing, and passivates defects. Consistent with this picture, coSAMu promotes a more favorable vertical composition near the ITO surface and suppresses trap-assisted recombination, enabling more efficient charge extraction and collection. Consequently, a representative D18:L8-BO OSC incorporating the sequential-cast coSAMu HTL achieves a power conversion efficiency of 20.1% (0.042 cm2), outperforming pristine 2PACz. Importantly, when scaled to a 17.14 cm2 mini-module (six serially connected subcells), coSAMu delivers 17.0% efficiency versus 12.2% for the 2PACz control. This work demonstrates controlled multilayer co-assembly as an effective strategy for scalable OSC interface engineering that is broadly applicable to multiple donor–acceptor systems. (Figure presented.)
Scalable photovoltaics
Organic solar cells
Trap passivation
Interface engineering
Self-assembled monolayers
Author
Jingnan Wu
Chalmers, Chemistry and Chemical Engineering, Applied Chemistry
Fengbo Sun
Shandong University
Leandro Rezende Franco
Chalmers, Chemistry and Chemical Engineering, Applied Chemistry
Qiaonan Chen
Chalmers, Chemistry and Chemical Engineering, Applied Chemistry
Xinxin Xia
Shandong University
Ruike Zhou
Jianghan University
Zhuang Li
Jianghan University
Mateus Bergami
Karlstad University
Pablo Hermosilla Fernandez
Chalmers, Chemistry and Chemical Engineering, Applied Chemistry
C. Moyses Araujo
Uppsala University
Karlstad University
Biao Xiao
Jianghan University
Xunchang Wang
Jianghan University
Donghong Yu
Sino-Danish Center for Education and Research Denmark
Aalborg University
Maojie Zhang
Shandong University
Renqiang Yang
Jianghan University
Ergang Wang
Chalmers, Chemistry and Chemical Engineering
Nano-Micro Letters
23116706 (ISSN) 21505551 (eISSN)
Vol. 19 1 29Subject Categories (SSIF 2025)
Condensed Matter Physics
DOI
10.1007/s40820-026-02325-2
Related datasets
Supplementary material [dataset]
URI: https://media.springernature.com/original/springer-static/esm/art%3A10.1007%2Fs40820-026-02325-2/MediaObjects/40820_2026_2325_MOESM1_ESM.pdf