Charge-Transfer Enhancement by PEI/MXene Buffer Layer for Boosting Performance of Inverted Perovskite Solar Cells

Area of Science:

• Materials Science
• Renewable Energy
• Nanotechnology

Background:

• Polyethylenimine (PEI) is a potential buffer layer material for perovskite solar cells (PSCs), improving energy alignment via amine-induced dipoles.
• The insulating nature of PEI can increase series resistance, hindering device performance.
• Optimizing the interface between PCBM and the metal cathode is crucial for high-performance PSCs.

Purpose of the Study:

• To develop a solution-processable buffer layer combining PEI with Ti3C2Tx MXene (PEI/MX) for inverted PSCs.
• To investigate the impact of PEI/MX on interfacial properties and photovoltaic performance.
• To enhance the power conversion efficiency (PCE) and stability of PSCs.

Main Methods:

• Fabrication of inverted PSCs using PEI/MX as a cathode buffer layer.
• Characterization using electrical and spectroscopic techniques to analyze interfaces (PCBM/PEI/MX/Ag).
• Performance evaluation of PSCs, including power conversion efficiency (PCE), open-circuit voltage (Voc), and fill factor (FF).

Main Results:

• The PEI/MX buffer layer successfully optimized the PCBM/PEI/MX/Ag interfaces.
• Interfacial improvements led to suppressed recombination losses and enhanced charge carrier dynamics.
• PEI/MX based PSCs achieved a significantly higher PCE (22.0 ± 0.8%, champion 23.1%) compared to PEI-only devices (18.9 ± 0.6%).

Conclusions:

• Solution-processable PEI/MX composite is a highly effective cathode buffer layer for high-performance PSCs.
• The incorporation of MXene into PEI mitigates the insulating drawbacks of PEI while enhancing interfacial properties.
• PEI/MX offers a promising alternative to conventional buffer layer materials for advancing PSC technology.