Multimodal host-guest complexation for efficient and stable perovskite photovoltaics

Area of Science:

• Materials Science
• Photovoltaics
• Supramolecular Chemistry

Background:

• Formamidinium lead iodide perovskites are promising light-harvesting materials for solar cells.
• Stabilizing these perovskites under operating conditions without compromising optoelectronic properties is a significant challenge.
• Defect passivation and phase stabilization are crucial for high-performance and durable perovskite solar cells.

Purpose of the Study:

• To develop a novel strategy for stabilizing formamidinium lead iodide perovskites.
• To improve the optoelectronic properties and operational stability of perovskite solar cells.
• To explore the application of host-guest chemistry in photovoltaic materials.

Main Methods:

• A multimodal host-guest complexation strategy was employed using dibenzo-21-crown-7 (host) and Cs+ ions (guest).
• The crown ether assembled at the interface, delivering Cs+ ions and modulating the perovskite material.
• This created a nanoscale doping gradient, passivated defects, and stabilized the perovskite phase.

Main Results:

• The strategy resulted in a local gradient of doping at the nanoscale, enhancing photoinduced charge separation.
• Surface and bulk defects were passivated, leading to a stabilized perovskite phase through synergistic effects.
• The resulting solar cells achieved power conversion efficiencies exceeding 24% and maintained over 95% performance for 500 hours without encapsulation.

Conclusions:

• The supramolecular host-guest complexation strategy effectively stabilizes formamidinium lead iodide perovskites.
• This approach significantly enhances solar cell efficiency and operational stability.
• The host molecule's ability to bind lead ions offers potential for reduced environmental impact in photovoltaics.