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Vol. 17 (2025)

Reducing the Voc Loss of Hole Transport Layer-Free Carbon-Based Perovskite Solar Cells via Dual Interfacial Passivation

https://doi.org/10.1007/s40820-025-01775-4
Xian Zhang
Key Laboratory of Materials Laminating Fabrication and Interface Control Technology of Tianjin, School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300401, People’s Republic of China
Fangzhou Liu
Key Laboratory of Materials Laminating Fabrication and Interface Control Technology of Tianjin, School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300401, People’s Republic of China
Yan Guan
College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, People’s Republic of China
Yu Zou
State Key Laboratory for Mesoscopic Physics and Department of Physics, Peking University, Beijing 100871, People’s Republic of China
Cuncun Wu
Key Laboratory of Materials Laminating Fabrication and Interface Control Technology of Tianjin, School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300401, People’s Republic of China
Dongchang Shi
Key Laboratory of Materials Laminating Fabrication and Interface Control Technology of Tianjin, School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300401, People’s Republic of China
Hongkai Zhang
Key Laboratory of Materials Laminating Fabrication and Interface Control Technology of Tianjin, School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300401, People’s Republic of China
Wenjin Yu
State Key Laboratory for Mesoscopic Physics and Department of Physics, Peking University, Beijing 100871, People’s Republic of China
Dechun Zou
College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, People’s Republic of China
Yangyang Zhang
Key Laboratory of Materials Laminating Fabrication and Interface Control Technology of Tianjin, School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300401, People’s Republic of China
Lixin Xiao
State Key Laboratory for Mesoscopic Physics and Department of Physics, Peking University, Beijing 100871, People’s Republic of China
Shijian Zheng
Key Laboratory of Materials Laminating Fabrication and Interface Control Technology of Tianjin, School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300401, People’s Republic of China

Corresponding Author: Shijian Zheng

sjzheng@hebut.edu.cn

Nano-Micro Letters, Vol. 17 (2025), Article Number: 258

Abstract

The hole transport layer (HTL)-free carbon-based perovskite solar cells (C-PSCs) are promising for commercialization owing to their excellent operational stability and simple fabrication process. However, the power conversion efficiencies (PCE) of C-PSCs are inferior to the metal electrode-based devices due to their open-circuit voltage (Voc) loss. Herein, time-resolved confocal photoluminescence microscopy reveals that grain boundary defects at the perovskite/carbon interface are very likely to function as nonradiative recombination centers in HTL-free C-PSCs. A versatile additive Li2CO3 is used to modify the conformal tin oxide electron transport layer for HTL-free C-PSCs. Li2CO3 modification can result in enhanced charge extraction and optimized energy alignment at electron transport layer/perovskite interface, as well as suppressed defects at perovskite top surface due to Li2CO3-induced formation of PbI2 crystallites. Such dual interfacial passivation ultimately leads to significantly improved Voc up to 1.142 V, which is comparable to the metal electrode-based devices with HTL. Moreover, a record-high PCE of 33.2% is achieved for Li2CO3-modified C-PSCs under weak light illumination conditions, demonstrating excellent indoor photovoltaic performance. This work provides a practical approach to fabricate low-cost, highly efficient carbon-based perovskite solar cells.


Highlights:
1 Li2CO3 is used to modify conformal SnO2 as electron transport layer for hole transport layer-free carbon-based perovskite solar cells (C-PSCs).
2 CO32− can induce MA release from the perovskite layer, resulting in PbI2 at the grain boundary of top interface of perovskite film which can passivate the grain boundary and the top surface defects.
3 The Li2CO3-modified C-PSC exhibits a high power conversion efficiency (PCE) of 19.1%, with a Voc of 1.142 V. A record-high PCE of 33.2% is obtained under weak light-emitting diode illumination (2000 lx, 3000 K).

Keywords

Perovskite solar cells Carbon electrode Hole transport layer-free Open-circuit voltage Indoor photovoltaic
Zhang, Xian, Fangzhou Liu, Yan Guan, Yu Zou, Cuncun Wu, Dongchang Shi, Hongkai Zhang, Wenjin Yu, Dechun Zou, Yangyang Zhang, Lixin Xiao, and Shijian Zheng. 2025. “Reducing the Voc Loss of Hole Transport Layer-Free Carbon-Based Perovskite Solar Cells via Dual Interfacial Passivation”. Nano-Micro Letters 17 (May):258. https://doi.org/10.1007/s40820-025-01775-4.
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