Tailoring Perovskite Surface Potential and Chelation Advances Efficient Solar Cells

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• Organic ammonium halide cations enhance perovskite solar cell performance.
• The effect of cation structural symmetry on perovskite interfaces is not well understood.

Purpose of the Study:

• To investigate how structural symmetry of organic ammonium halide cations influences perovskite solar cell performance.
• To compare the effects of symmetrical bis(2-chloroethyl)ammonium cation (B(CE)A+) and asymmetrical 2-chloroethylammonium cation (CEA+) on perovskite interfaces.

Main Methods:

• Utilized symmetrical B(CE)A+ and asymmetrical CEA+ cations as interface layers between perovskite and hole transport layers.
• Analyzed surface potential, chelation with Pb2+, energy band alignment, and defect healing.
• Measured power conversion efficiency (PCE) and operational stability.

Main Results:

• Symmetrical B(CE)A+ cations created a more homogeneous surface potential and better chelation with Pb2+ compared to asymmetrical cations.
• This resulted in improved energy band alignment, enhanced defect healing, and reduced nonradiative recombination.
• Perovskite solar cells with B(CE)A+ achieved a PCE of 25.60% and retained 91% efficiency after 500 hours of operation.

Conclusions:

• Structural symmetry of interface cations is crucial for optimizing perovskite solar cell performance and stability.
• Symmetrical cations promote efficient hole carrier extraction and suppress recombination.
• This strategy offers a promising route for developing high-performance and durable perovskite solar cells.