High performance planar p-i-n perovskite solar cells based on a thin Alq₃ cathode buffer layer.

Area of Science:

• Materials Science
• Renewable Energy
• Solid-State Physics

Background:

• Planar p-i-n perovskite solar cells (PSCs) are a promising photovoltaic technology.
• Efficient charge extraction at the cathode is crucial for high PSC performance.
• Tris-(8-hydroxyquinoline), aluminum (Alq3) is explored as a cathode buffer layer (CBL).

Purpose of the Study:

• To investigate the effect of incorporating a thin Alq3 CBL in planar PSCs.
• To analyze the impact of Alq3 on device performance metrics, particularly fill factor (FF) and power conversion efficiency (PCE).
• To elucidate the mechanism behind performance enhancement using AC impedance and transient photocurrent measurements.

Main Methods:

• Fabrication of planar p-i-n PSCs with the structure ITO/PEDOT:PSS/CH3NH3PbI3(Cl)/PCBM/Alq3/Ag.
• Characterization of device performance, including FF and PCE.
• Analysis using AC impedance spectra and transient photocurrent measurements.

Main Results:

• A high-performance planar PSC was achieved with FF of 72% and PCE of 14.22% using an Alq3 CBL.
• The PCE represents a 29% improvement compared to devices without the Alq3 CBL.
• AC impedance and photocurrent measurements indicated improved charge extraction at the cathode due to Alq3, reducing charge accumulation.

Conclusions:

• The integration of a thin Alq3 CBL effectively enhances the performance of planar PSCs.
• Alq3 facilitates better charge extraction at the cathode, leading to reduced charge accumulation and improved device efficiency.
• This study highlights Alq3 as a viable material for optimizing PSC architecture and performance.