Reducing Defects Density and Enhancing Hole Extraction for Efficient Perovskite Solar Cells Enabled by π-Pb²⁺...

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• Molecular doping is crucial for enhancing perovskite solar cell performance by reducing defects and improving charge extraction.
• Existing doping methods face challenges in defect passivation and interfacial engineering.

Purpose of the Study:

• To introduce a novel chemical doping strategy for perovskite solar cells using a specifically designed organic small molecule.
• To investigate the mechanism of doping, focusing on intermolecular π-Pb²⁺ interactions and their impact on perovskite properties.

Main Methods:

• Chemical doping of perovskite films with a novel organic small molecule featuring a fused tricyclic core.
• Characterization of perovskite films and solar cell devices.
• Density functional theory (DFT) calculations to understand doping mechanisms and interactions.

Main Results:

• The organic dopant formed strong π-Pb²⁺ interactions with under-coordinated Pb²⁺ in perovskite, reducing defect density.
• Nonradiative recombination was suppressed, and surface potential was deepened, downshifting the work function of the perovskite film.
• The doped perovskite solar cells achieved a high power conversion efficiency of 21.41% with negligible hysteresis.

Conclusions:

• The developed fused tricyclic core-based doping strategy effectively passivates defects and enhances interfacial charge extraction in perovskite solar cells.
• The π-Pb²⁺ interaction mechanism offers a new pathway for designing organic materials to boost solar cell performance.
• This approach presents a promising route for advancing perovskite solar cell technology.