Layered Defect-Filling co-Assembled Carbazole-Based SAMs Deliver 20% Organic Solar Cells and 17% Mini-Modules.

Authors

Jingnan Wu, Fengbo Sun, Leandro R Franco, Qiaonan Chen, Xinxin Xia, Ruike Zhou, Zhuang Li, Mateus Bergami, Pablo Hermosilla Fernandez, C Moyses Araujo, Biao Xiao, Xunchang Wang, Donghong Yu, Maojie Zhang, Renqiang Yang, Ergang Wang

Published in

Nano-micro letters. Volume 19. Issue 1. Aug 10, 2026. Epub Aug 10, 2026.

Abstract

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.

PMID:
42573849
Bibliographic data and abstract were imported from PubMed on 10 Aug 2026.

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