Regulating Surface Termination for Efficient Inverted Perovskite Solar Cells with Greater Than 23% Efficiency

Area of Science:

• Materials Science
• Photovoltaics
• Chemistry

Background:

• Perovskite solar cells (PVSCs) suffer from efficiency losses due to surface and bulk defects.
• Defect passivation is crucial for minimizing nonradiative recombination and enhancing device performance.
• Surface atomic periodicity disruptions impact perovskite material properties and device efficiency.

Purpose of the Study:

• To introduce a bifunctional molecule, piperazinium iodide (PI), for effective defect passivation in PVSCs.
• To investigate the impact of PI on perovskite film properties and device performance.
• To enhance the power conversion efficiency (PCE) and stability of inverted PVSCs.

Main Methods:

• Design and synthesis of a bifunctional molecule (piperazinium iodide) with electron donor and acceptor groups.
• Application of PI for surface defect passivation on perovskite films.
• Characterization of passivated perovskite films and fabricated inverted PVSCs.

Main Results:

• PI effectively passivates surface and bulk defects, reducing nonradiative recombination losses.
• Passivated films exhibit reduced surface residual stress and enhanced n-type characteristics.
• Achieved a high open-circuit voltage (V_OC) of 1.17 V with reduced V_OC loss (0.33 V).
• Attained a record power conversion efficiency (PCE) of 23.37% (22.75% certified) for inverted PVSCs.

Conclusions:

• Piperazinium iodide is a highly effective bifunctional passivator for perovskite solar cells.
• Simultaneous enhancement of device performance and stability is achievable with rationally designed molecules.
• This strategy offers a promising pathway for advancing high-efficiency perovskite photovoltaics.