Issue

Vol. 19 (2027)

Covalent Organic Framework-Anchored Carbon Nanotubes Enabling Ultra-Thin Robust Polyimide Films for High-Specific-Power Flexible GaAs Solar Cells

https://doi.org/10.1007/s40820-026-02326-1
Bin Li
Henan Key Laboratory of Information Functional Materials and Sensing Technology, Zhengzhou University of Light Industry, Zhengzhou 450002, People’s Republic of China
Zhejun Guo
Research Center for Photovoltaics, Shanghai Institute of Space Power-Sources, Shanghai 200245, People’s Republic of China
Qin Wang
College of Engineering Science and Technology, Shanghai Ocean University, Shanghai 201306, People’s Republic of China
Maoshu Yin
Research Center for Photovoltaics, Shanghai Institute of Space Power-Sources, Shanghai 200245, People’s Republic of China
Xianglei Shi
Research Center for Photovoltaics, Shanghai Institute of Space Power-Sources, Shanghai 200245, People’s Republic of China
Lu Yao
Faculty of Chemical Engineering and Energy Technology, Shanghai Institute of Technology, Shanghai 201418, People’s Republic of China
Chongjing Lu
Key Laboratory of Intelligent Creation for Extreme Energy Materials (Ministry of Education), Shanghai Jiao Tong University, Shanghai 200240, People’s Republic of China
Yanpeng Zhang
Henan Key Laboratory of Information Functional Materials and Sensing Technology, Zhengzhou University of Light Industry, Zhengzhou 450002, People’s Republic of China
Wenwei Xu
Research Center for Photovoltaics, Shanghai Institute of Space Power-Sources, Shanghai 200245, People’s Republic of China
Liying Jiang
Henan Key Laboratory of Information Functional Materials and Sensing Technology, Zhengzhou University of Light Industry, Zhengzhou 450002, People’s Republic of China
Lijie Sun
Research Center for Photovoltaics, Shanghai Institute of Space Power-Sources, Shanghai 200245, People’s Republic of China
Feng Shao
Faculty of Chemical Engineering and Energy Technology, Shanghai Institute of Technology, Shanghai 201418, People’s Republic of China
Xuan Liu
College of Engineering Science and Technology, Shanghai Ocean University, Shanghai 201306, People’s Republic of China
Nantao Hu
Key Laboratory of Intelligent Creation for Extreme Energy Materials (Ministry of Education), Shanghai Jiao Tong University, Shanghai 200240, People’s Republic of China

Corresponding Author: Nantao Hu

hunantao@sjtu.edu.cn

Nano-Micro Letters, Vol. 19 (2027), Article Number: 31

Abstract

Free-standing polymer films that are ultra-thin, lightweight, and robust hold significant promise for applications in flexible electronics. However, their performance has been constrained by the challenge of simultaneously enhancing mechanical strength and reducing density. Herein, an ultra-thin and robust polyimide (PI)-based covalent organic framework-modified multi-walled carbon nanotube (MWCNT-COF) film is demonstrated for high-specific-power flexible GaAs solar cells. The film exhibits a high Young’s modulus of 1.53 GPa, a tensile strength exceeding 97.53 MPa, and a low density of 0.73 g cm−3, representing a 45.1% reduction in density. The incorporation of 3D interconnected layered and porous MWCNT-COF significantly enhances the film’s mechanical properties while reducing its density. The synergistic effects of robust MWCNTs and covalently bonded COF layers, combined with the thermally stable PI molecular structure, impart exceptional strength and lightness to the film. Computational studies further confirm that COF-grafted MWCNTs effectively modify the polyamide acid matrix, substantially improving the mechanical properties of the PI films. Moreover, flexible dual-junction and triple-junction GaAs solar cells were successfully fabricated using 6 µm-thick MWCNT-COF/PI composite films, delivering outstanding specific powers of 8998 and 7749 W kg−1, along with efficiencies of 26.6% and 31.5% (AM0), respectively. These results underscore the potential for high-performance applications in space and energy systems. This work offers valuable insights into the development of high-performance flexible GaAs solar cells based on ultra-thin and robust PI films for a wide range of applications.


Highlights:
1 A scalable solvothermal route is proposed for directly growing covalent organic framework (COF) shells on carboxylated multi-walled carbon nanotube (MWCNT), yielding MWCNT-COF hybrids with high thermal stability.
2 Polyimide composite films demonstrate a tensile strength of 97.5 MPa, a modulus of 1.53 GPa, and a density of 0.73 g cm⁻³, resolving the strength–density dilemma.
3 Flexible dual-junction and triple-junction GaAs solar cells achieve ultrahigh specific powers of 8998 and 7749 W kg⁻¹, respectively, with minimal performance degradation after 2000 bending cycles at a 10 mm radius.

Keywords

Covalent organic frameworks Carbon nanotubes Polyimide Composite films High-specific-power flexible solar cell
Li, Bin, Zhejun Guo, Qin Wang, Maoshu Yin, Xianglei Shi, Lu Yao, Chongjing Lu, Yanpeng Zhang, Wenwei Xu, Liying Jiang, Lijie Sun, Feng Shao, Xuan Liu, and Nantao Hu. 2026. “Covalent Organic Framework-Anchored Carbon Nanotubes Enabling Ultra-Thin Robust Polyimide Films for High-Specific-Power Flexible GaAs Solar Cells”. Nano-Micro Letters 19 (August):31. https://doi.org/10.1007/s40820-026-02326-1.
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