Efficient and Stable β-CsPbI
Yifan Lv1, Yiqun Li1, Yan Zhou1
1Key Laboratory of Flexible Electronics (KLOFE) & Institution of Advanced Materials (IAM), School of Flexible Electronics (Future Technologies), Nanjing Tech University (NanjingTech), Nanjing, Jiangsu 211816, P.R. China.
ACS Applied Materials & Interfaces
|June 8, 2023
Summary
Cesium lead iodide (CsPbI3) perovskite thin films were stabilized in their photoactive phase using MAAc solvent. This method enhances perovskite solar cell efficiency and stability, crucial for photovoltaic applications.
Area of Science:
- Materials Science
- Photovoltaics
- Solid-State Chemistry
Background:
- Cesium lead iodide (CsPbI3) is a promising perovskite material for solar cells due to its band gap and thermal stability.
- CsPbI3 is prone to phase transitions from its photoactive to photoinactive state, especially in humid conditions, limiting device performance.
- Controllable growth of CsPbI3 thin films in the desired β-crystal phase and with compact morphology is essential for efficient and stable perovskite solar cells (PSCs).
Purpose of the Study:
- To develop a method for the controllable growth of β-CsPbI3 perovskite thin films.
- To enhance the phase stability and morphology of CsPbI3 for improved PSC performance.
- To investigate the role of solvent and coordination in stabilizing the photoactive phase of CsPbI3.
Main Methods:
- Utilized MAAc (N-methylacetamide) as a solvent for the CsPbI3 precursor solution.
- Investigated the formation of an intermediate compound (CsxMA1-xPbIxAc3-x) during solution processing.
- Analyzed the effect of annealing on ion exchange and phase transformation.
- Studied the role of C═O···Pb coordination in stabilizing the β-CsPbI3 phase.
Main Results:
- Fabricated β-CsPbI3 perovskite thin films using MAAc solvent, leading to controllable growth.
- Observed the formation of an intermediate compound and subsequent ion exchange during annealing.
- Demonstrated that C═O···Pb coordination stabilizes the black-phase β-CsPbI3.
- Achieved PSCs with a power conversion efficiency of 18.9%.
- Exhibited improved device stability, with <10% efficiency decay after 2000 h in N2 and <30% decay after 500 h in humid air without encapsulation.
Conclusions:
- MAAc solvent facilitates the formation of stable β-CsPbI3 perovskite thin films.
- Strong C═O···Pb coordination is key to stabilizing the photoactive phase and promoting desired crystal growth.
- The developed method significantly enhances both the efficiency and stability of CsPbI3-based PSCs, paving the way for practical applications.
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