Issue

Vol. 18 (2026)

Differentiating the 2D Passivation from Amorphous Passivation in Perovskite Solar Cells

https://doi.org/10.1007/s40820-025-01913-y
Xiaojian Zheng
College of New Materials and New Energies, Shenzhen Technology University, Lantian Road 3002, Pingshan 518118, Shenzhen, People’s Republic of China
Shehzad Ahmed
China-UK Low Carbon College, Shanghai Jiao Tong University, Lingang 201306, Shanghai, People’s Republic of China
Yu Zhang
College of New Materials and New Energies, Shenzhen Technology University, Lantian Road 3002, Pingshan 518118, Shenzhen, People’s Republic of China
Guoqiang Xu
College of New Materials and New Energies, Shenzhen Technology University, Lantian Road 3002, Pingshan 518118, Shenzhen, People’s Republic of China
Junyu Wang
College of New Materials and New Energies, Shenzhen Technology University, Lantian Road 3002, Pingshan 518118, Shenzhen, People’s Republic of China
Di Lu
College of New Materials and New Energies, Shenzhen Technology University, Lantian Road 3002, Pingshan 518118, Shenzhen, People’s Republic of China
Tingshu Shi
College of New Materials and New Energies, Shenzhen Technology University, Lantian Road 3002, Pingshan 518118, Shenzhen, People’s Republic of China
Jun Tang
College of New Materials and New Energies, Shenzhen Technology University, Lantian Road 3002, Pingshan 518118, Shenzhen, People’s Republic of China
Lei Yan
Engineering and Research Center for Integrated New Energy Photovoltaics & Energy Storage Systems of Hunan Province and School of Electrical Engineering, University of South China, Hengyang 421001, People’s Republic of China
Wei Chen
College of Engineering Physics, Shenzhen Technology University, Shenzhen 518118, Guangdong, People’s Republic of China
Peigang Han
College of New Materials and New Energies, Shenzhen Technology University, Lantian Road 3002, Pingshan 518118, Shenzhen, People’s Republic of China
Zhixin Liu
College of New Materials and New Energies, Shenzhen Technology University, Lantian Road 3002, Pingshan 518118, Shenzhen, People’s Republic of China
Danish Khan
College of New Materials and New Energies, Shenzhen Technology University, Lantian Road 3002, Pingshan 518118, Shenzhen, People’s Republic of China
Xingzhu Wang
Engineering and Research Center for Integrated New Energy Photovoltaics & Energy Storage Systems of Hunan Province and School of Electrical Engineering, University of South China, Hengyang 421001, People’s Republic of China
Zeguo Tang
College of New Materials and New Energies, Shenzhen Technology University, Lantian Road 3002, Pingshan 518118, Shenzhen, People’s Republic of China

Corresponding Author: Zeguo Tang

tangzeguo@sztu.edu.cn

Nano-Micro Letters, Vol. 18 (2026), Article Number: 62

Abstract

The introduction of two-dimensional (2D) perovskite layers on top of three-dimensional (3D) perovskite films enhances the performance and stability of perovskite solar cells (PSCs). However, the electronic effect of the spacer cation and the quality of the 2D capping layer are critical factors in achieving the required results. In this study, we compared two fluorinated salts: 4-(trifluoromethyl) benzamidine hydrochloride (4TF-BA·HCl) and 4-fluorobenzamidine hydrochloride (4F-BA·HCl) to engineer the 3D/2D perovskite films. Surprisingly, 4F-BA formed a high-performance 3D/2D heterojunction, while 4TF-BA produced an amorphous layer on the perovskite films. Our findings indicate that the balanced intramolecular charge polarization, which leads to effective hydrogen bonding, is more favorable in 4F-BA than in 4TF-BA, promoting the formation of a crystalline 2D perovskite. Nevertheless, 4TF-BA managed to improve efficiency to 24%, surpassing the control device, primarily due to the natural passivation capabilities of benzamidine. Interestingly, the devices based on 4F-BA demonstrated an efficiency exceeding 25% with greater longevity under various storage conditions compared to 4TF-BA-based and the control devices.


Highlights:
1 Benzamidine derivatives are utilized to differentiate between 2D passivation and amorphous passivation.
2 Introducing an n-type 2D passivation layer enhances the charge extraction and transportation and reduces the interface recombination in inverted perovskite solar cells.
3 The intramolecular charge of organic ligands is critical for the formation of crystalline 2D capping layers on 3D perovskite layers.
4 The long-term stability of inverted perovskite solar cells is improved owing to hydrophobic sealing of 3D perovskite via crystalline 2D capping.








Keywords

3D/2D perovskite films Benzamidine Amorphous passivation 2D passivation Inverted perovskite solar cells
Zheng, Xiaojian, Shehzad Ahmed, Yu Zhang, Guoqiang Xu, Junyu Wang, Di Lu, Tingshu Shi, Jun Tang, Lei Yan, Wei Chen, Peigang Han, Zhixin Liu, Danish Khan, Xingzhu Wang, and Zeguo Tang. 2025. “Differentiating the 2D Passivation from Amorphous Passivation in Perovskite Solar Cells”. Nano-Micro Letters 18 (September):62. https://doi.org/10.1007/s40820-025-01913-y.
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