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Stoichiometry-Regulated Crystallization and Halide Homogenization in Wide-Bandgap Perovskites for Efficient Solar
Yuxiao Guo1, Yuliang Xu2, Haoran Yang3
1Key Laboratory for Soft Chemistry and Functional Materials of Ministry of Education, School of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing, Jiangsu 210094, P. R. China.
Optimizing precursor stoichiometry in perovskite solar cells (PSCs) enables efficient, stable wide-bandgap devices without additives. This control over crystallization pathways enhances performance for both single-junction and tandem applications.
Area of Science:
- Materials Science
- Renewable Energy
- Photovoltaics
Background:
- Efficient and stable wide-bandgap perovskite solar cells (WBG PSCs) are crucial for next-generation photovoltaics.
- Current advancements often rely on additives, with the intrinsic role of precursor stoichiometry being less understood.
Purpose of the Study:
- To investigate the impact of precursor stoichiometry on crystallization and halide distribution in WBG perovskites.
- To establish an additive-free method for controlling WBG perovskite film formation and device performance.
Main Methods:
- Systematic variation of the precursor stoichiometry (FAX to PbX2 ratio) in FA0.83Cs0.17Pb(IxBr1-x)3 perovskites.
- Analysis of crystallization kinetics, supersaturation, nucleation barriers, and film morphology.
- Fabrication and characterization of single-junction WBG PSCs and monolithic all-perovskite tandem solar cells.
Main Results:
- A specific stoichiometric regime (PbI2 to total PbX2 ratio of ~55-75%) was identified to minimize supersaturation and slow crystal growth.
- Optimized films exhibited full coverage, preferred crystallographic orientation, and reduced strain.
- Achieved high power conversion efficiencies for WBG PSCs (up to ~24.19%) and tandem cells (~29.10% with >80% stability over 400 hours).
Conclusions:
- Precursor stoichiometry is a key additive-free chemical lever for controlling WBG perovskite crystallization and device performance.
- This strategy provides a rational framework for developing highly efficient and stable single-junction and tandem perovskite solar cells.
