Defect passivation and crystallization modulation in methylammonium-free wide-bandgap perovskites for all-perovskite tandem solar cells

Xuefei Jia¹, Kaicheng Zhang², Xiaofeng Gao¹, Xufeng Liao¹, Yujie Yang³, Weisheng Li¹, Xiaojing Lv¹, Xinyu Zhao¹, Jiali Liu⁴, Yitong Ji¹, Zhongliang Yan⁵, Qingguo Du⁶, Fuzhi Huang^{1

7}, Zhiwei Ren⁸, Yaxin Zhai⁴, Wenchao Huang¹, Yang Bai⁵, Canglang Yao⁹, Qianqian Lin³, Yi-Bing Cheng^{1

7}, Jinhui Tong¹

Affiliations

¹ State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, P. R. China.
² Institute of Materials for Electronics and Energy Technology (i-MEET), Department of Materials Science and Engineering, Friedrich-Alexander-Universität Erlangen-Nürnberg, Martensstrasse 7, 91058 Erlangen, Germany.
³ Key Lab of Artificial Micro- and Nano-Structures of Ministry of Education of China, School of Physics and Technology, Wuhan University, Wuhan 430072, P. R. China.
⁴ Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education, Department of Physics, Hunan Normal University, Changsha 410081, P. R. China.
⁵ Faculty of Materials Science and Energy Engineering, Shenzhen University of Advanced Technology, Shenzhen 518107, China.
⁶ School of information engineering, Wuhan University of Technology, Wuhan 430070, P. R. China.
⁷ Foshan Xianhu Laboratory of the Advanced Energy Science and Technology, Guangdong Laboratory, Foshan 528216, P. R. China.
⁸ Department of Electrical and Electronic Engineering, Photonics Research Institute (PRI), Research Institute for Intelligent Wearable Systems (iWEAR), The Hong Kong Polytechnic University, Hong Kong 100872, P. R. China.
⁹ Laboratory of Advanced Materials, Fudan University, Shanghai 200438, P. R. China.

PMID: 40961199
PMCID: PMC12442863
DOI: 10.1126/sciadv.adv4501

Defect passivation and crystallization modulation in methylammonium-free wide-bandgap perovskites for all-perovskite tandem solar cells

Xuefei Jia et al. Sci Adv. 2025.

. 2025 Sep 19;11(38):eadv4501.

doi: 10.1126/sciadv.adv4501. Epub 2025 Sep 17.

Authors

Affiliations

¹ State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, P. R. China.
² Institute of Materials for Electronics and Energy Technology (i-MEET), Department of Materials Science and Engineering, Friedrich-Alexander-Universität Erlangen-Nürnberg, Martensstrasse 7, 91058 Erlangen, Germany.
³ Key Lab of Artificial Micro- and Nano-Structures of Ministry of Education of China, School of Physics and Technology, Wuhan University, Wuhan 430072, P. R. China.
⁴ Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education, Department of Physics, Hunan Normal University, Changsha 410081, P. R. China.
⁵ Faculty of Materials Science and Energy Engineering, Shenzhen University of Advanced Technology, Shenzhen 518107, China.
⁶ School of information engineering, Wuhan University of Technology, Wuhan 430070, P. R. China.
⁷ Foshan Xianhu Laboratory of the Advanced Energy Science and Technology, Guangdong Laboratory, Foshan 528216, P. R. China.
⁸ Department of Electrical and Electronic Engineering, Photonics Research Institute (PRI), Research Institute for Intelligent Wearable Systems (iWEAR), The Hong Kong Polytechnic University, Hong Kong 100872, P. R. China.
⁹ Laboratory of Advanced Materials, Fudan University, Shanghai 200438, P. R. China.

PMID: 40961199
PMCID: PMC12442863
DOI: 10.1126/sciadv.adv4501

Abstract

Wide-bandgap (WBG; >1.65 electron volts) perovskites based on iodine-bromine (I-Br) mixed halides are critical components of perovskite-based tandem solar cells (TSCs). However, the uncontrolled crystallization dynamics of Br-rich species lead to reduced grain sizes and high defect densities in WBG perovskite films. Herein, a multifunctional additive 3,4,5-trifluorobenzamide (TFBZ) was introduced to enhance the crystallinity and passivate defects of the methylammonium (MA)-free WBG perovskite films. The TFBZ demonstrates superior passivation capability compared to benzamide, effectively mitigating both iodine vacancies and undercoordinated Pb²⁺ defects via fluorine-enhanced interactions. In addition, the fluorine substituents in TFBZ could form N-H···F hydrogen bonds with formamidinium iodide to retard the crystallization rate of the perovskite. This proposed method is effective in defect passivation and crystal growth modulation for both 1.67- and 1.79-electron volt MA-free WBG perovskites, enabling the fabrication of MA-free all-perovskite TSCs with an encouraging power conversion efficiency of 29.01% (certified at 28.52%).

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Figures

**Fig. 1.. Molecular structures of additives and their interaction with perovskite.**
(A) Molecular structures of BZD and TFBZ. (B) Density functional theory (DFT) calculations of the adsorption energies between the FAI termination and BZD/TFBZ molecules. (C) DFT calculations of the adsorption energies between the PbI₂ termination and BZD/TFBZ molecules. (D) Partial enlarged view of the Fourier transform infrared (FTIR) spectra for TFBZ and BZD, as well as their mixtures with perovskite. (E) Partial enlarged view of ¹H nuclear magnetic resonance (NMR) spectra for BZD, TFBZ, and their mixtures with FAI and PbI₂ in DMSO-d₆ solvent. (F) X-ray photoelectron spectroscopy (XPS) spectra of Pb 4f and I 3d for perovskite films with and without TFBZ/BZD addition. a.u., arbitrary unit.

**Fig. 2.. Effect of additives on the nucleation, crystallization, and morphology of perovskite films.**
(A) 2D contour maps of in situ UV-vis transmission spectra for the control, w/BZD, and w/TFBZ during spin coating. (B) Top-view scanning electron microscopy (SEM) images of control, w/BZD, and w/TFBZ perovskite films. The insets show the grain size distributions. (C) Cross-sectional SEM images of control, w/BZD, and w/TFBZ perovskite films. (D) Schematic illustration of the crystallization processes in control and TFBZ-modified perovskite films. a.u., arbitrary unit.

**Fig. 3.. Carrier dynamics and nonradiative recombination of WBG perovskite thin films.**
(A) The pseudocolor representation of TA spectral evolution for the control, w/BZD, and w/TFBZ perovskite films. (B) Normalized surface carrier kinetics of the control, w/BZD, and w/TFBZ perovskite films photoexcited at the indicated wavelength (solid traces are nonlinear least-squares global best-fit curves). (C) Time-resolved microwave conductivity (TRMC) decays of the control, w/BZD, and w/TFBZ perovskite films. (D) Charge carrier mobilities of the control, w/BZD, and w/TFBZ perovskite films. (E) TRPL spectra of the control, w/BZD, and w/TFBZ perovskite films. a.u., arbitrary unit.

**Fig. 4.. Stability of WBG perovskite thin films.**
(A) PL spectra of the control, w/BZD, and w/TFBZ perovskite films under continuous illumination for different times. (B) Ion migration activation energy of the control, w/BZD, and w/TFBZ perovskite films. (C) The evolution of photographs of the WBG perovskite films stored at 25°C and under 85% relative humidity (RH). (D) Water contact angles of the control, w/BZD, and w/TFBZ perovskite films. h, hours. a.u., arbitrary unit.

**Fig. 5.. Structure and performance of MA-free WBG perovskite and all-perovskite tandem devices.**
(A) Cross-sectional SEM image of the 1.67-eV PSC device with the following structure: ITO/NiO_x/Me-4PACz/perovskite/LiF/C₆₀/BCP/Ag. (B) *J-V* curves of the best-performing devices for control, w/BZD, and w/TFBZ. (C) Statistical box plot of PCEs. (D) MPP test performed under a xenon lamp without filters at 1 sun for the encapsulated control, w/BZD, and w/TFBZ devices. (E) Ambient stability test performed under 25° ± 5°C and 20 ± 5% RH for the unencapsulated control, w/BZD, and w/TFBZ devices. (F) Cross-sectional SEM image of the MA-free all-perovskite tandem device. TRJ, tunnel recombination junction. (G) *J-V* curves of the best-performing all-perovskite tandem devices without and with TFBZ. (H) Comparison of PCE and V_OC of the champion device achieved in this work with reported high-performance all-perovskite tandem devices (source data are from tables S12 and S13).

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References

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Defect passivation and crystallization modulation in methylammonium-free wide-bandgap perovskites for all-perovskite tandem solar cells

Affiliations

Defect passivation and crystallization modulation in methylammonium-free wide-bandgap perovskites for all-perovskite tandem solar cells

Authors

Affiliations

Abstract

Figures

References