Alkylammonium Spacer-Directed Charge-Transfer in 2D|3D Perovskite Solar Cells

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• Long-term stability remains a critical challenge for Perovskite Solar Cells (PSCs).
• Two-dimensional|three-dimensional (2D|3D) perovskite heterostructures offer a promising strategy by combining the efficiency of 3D phases with the durability of 2D layers.

Purpose of the Study:

• To systematically investigate the role of two alkylammonium spacers, butylammonium iodide (BAI) and butyl-1,4-diammonium diiodide (BDAI2), in 2D|3D PSCs.
• To elucidate the impact of spacer chemistry and concentration on device efficiency, stability, and charge transport mechanisms.

Main Methods:

• Fabrication of 2D|3D perovskite heterostructures using varying concentrations of BAI and BDAI2 spacers.
• Characterization techniques including photoluminescence, conductive atomic force microscopy, and electrochemical impedance spectroscopy.
• Device performance testing and long-term durability assessments under ambient conditions.

Main Results:

• Low spacer concentrations acted as surface passivators, yielding efficiencies comparable to pristine PSCs.
• High BAI concentrations promoted structural flexibility and improved moisture resistance, enhancing device stability.
• High BDAI2 concentrations led to rapid degradation and introduced insulating barriers, hindering charge transport.

Conclusions:

• Spacer chemistry and concentration critically influence the trade-off between charge transport and environmental resilience in 2D|3D PSCs.
• Optimized spacer concentrations can suppress nonradiative recombination without compromising conductivity.
• BAI demonstrates potential for prolonging PSC device lifetime, offering insights for designing durable perovskite photovoltaics.