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Vol. 17 (2025)

Dicyandiamide-Driven Tailoring of the n-Value Distribution and Interface Dynamics for High-Performance ACI 2D Perovskite Solar Cells

https://doi.org/10.1007/s40820-025-01817-x
Ge Chen
College of Chemistry, Zhengzhou University, Zhengzhou 450001, People’s Republic of China
Yunlong Gan
College of Chemistry, Zhengzhou University, Zhengzhou 450001, People’s Republic of China
Shiheng Wang
College of Chemistry, Zhengzhou University, Zhengzhou 450001, People’s Republic of China
Xueru Liu
College of Chemistry, Zhengzhou University, Zhengzhou 450001, People’s Republic of China
Jing Yang
College of Chemistry, Zhengzhou University, Zhengzhou 450001, People’s Republic of China
Sihui Peng
College of Chemistry, Zhengzhou University, Zhengzhou 450001, People’s Republic of China
Yingjie Zhao
College of Chemistry, Zhengzhou University, Zhengzhou 450001, People’s Republic of China
Pengwei Li
College of Chemistry, Zhengzhou University, Zhengzhou 450001, People’s Republic of China
Asliddin Komilov
Karshi State Technical University, 18100 Karshi, Uzbekistan
Yanlin Song
Key Laboratory of Green Printing, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Beijing Engineering Research Center of Nanomaterials for Green Printing Technology, National Laboratory for Molecular Sciences (BNLMS), Chinese Academy of Sciences (ICCAS), Beijing 100190, People’s Republic of China
Yiqiang Zhang
College of Chemistry, Zhengzhou University, Zhengzhou 450001, People’s Republic of China

Corresponding Author: Yiqiang Zhang

yqzhang@zzu.edu.cn

Nano-Micro Letters, Vol. 17 (2025), Article Number: 305

Abstract

Organic–inorganic hybrid perovskite solar cells achieve remarkable efficiencies (> 26%) yet face stability challenges. Quasi-2D alternating-cation-interlayer perovskites offer enhanced stability through hydrophobic spacer cations but suffer from vertical phase segregation and buried interface defects. Herein, we introduce dicyanodiamide (DCD) to simultaneously address these dual limitations in GA(MA)nPbnI3n+1 perovskites. The guanidine group in DCD passivates undercoordinated Pb2+ and MA+ vacancies at the perovskite/TiO2 interface, while cyano groups eliminate oxygen vacancies in TiO2 via Ti4+–CN coordination, reducing interfacial trap density by 73% with respect to the control sample. In addition, DCD regulates crystallization kinetics, suppressing low-n-phase aggregation and promoting vertical alignment of high-n phases, which benefit for carrier transport. This dual-functional modification enhances charge transport and stabilizes energy-level alignment. The optimized devices achieve a record power conversion efficiency of 21.54% (vs. 19.05% control) and retain 94% initial efficiency after 1200 h, outperforming unmodified counterparts (84% retention). Combining defect passivation with phase homogenization, this work establishes a molecular bridge strategy to decouple stability-efficiency trade-offs in low-dimensional perovskites, providing a universal framework for interface engineering in high-performance optoelectronics.


Highlights:
1 Guanidine derivatives of dicyanodiamide (DCD) is introduced into the buried interface of quasi-2D alternating-cation-interlayer perovskites (GA(MA)nPbnI3n+1), which simultaneously realize the defect passivation of buried interface and the regulation of phase distribution.
2 This interface engineering not only reduces interfacial defects but also enhances the interfacial charge transfer, and the DCD-regulated perovskite solar cells exhibit a significant increase in efficiency from 19.05% to 21.54%.

Keywords

Alternating-cation-interlayer 2D perovskite solar cell Phase modulation Buried interface Interface dynamics
Chen, Ge, Yunlong Gan, Shiheng Wang, Xueru Liu, Jing Yang, Sihui Peng, Yingjie Zhao, Pengwei Li, Asliddin Komilov, Yanlin Song, and Yiqiang Zhang. 2025. “Dicyandiamide-Driven Tailoring of the N-Value Distribution and Interface Dynamics for High-Performance ACI 2D Perovskite Solar Cells”. Nano-Micro Letters 17 (June):305. https://doi.org/10.1007/s40820-025-01817-x.
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