Dual Defect-Passivation Using Phthalocyanine for Enhanced Efficiency and Stability of Perovskite Solar Cells

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• Perovskite solar cells (PSCs) efficiency and stability are often limited by defects in the perovskite film.
• Passivation strategies using semiconducting molecules are crucial for overcoming these limitations.

Purpose of the Study:

• To demonstrate a molecular design strategy for passivating surface and interior defects in methylammonium lead iodide (CH₃ NH₃ PbI₃) perovskite films.
• To investigate the use of two specific phthalocyanine (Pc) molecules, NP-SC₆ -ZnPc and NP-SC₆ -TiOPc, as defect passivating agents.

Main Methods:

• Utilized density functional theory (DFT) calculations to study the interaction of Pc molecules with the perovskite surface.
• Employed Pc molecules (NP-SC₆ -ZnPc and NP-SC₆ -TiOPc) for defect passivation of the perovskite layer.
• Characterized the morphology and surface roughness of the passivated perovskite films.

Main Results:

• Phthalocyanine molecules, through Lewis acid-base interactions with under-coordinated Pb²⁺ sites, efficiently passivated perovskite defects.
• The Pc passivation strategy improved perovskite film morphology, resulting in dense, compact films with reduced surface roughness.
• Power conversion efficiencies (PCEs) increased from 17.67% for pristine PSCs to 19.39% for NP-SC₆ -TiOPc passivated PSCs.

Conclusions:

• The developed Pc passivation strategy significantly enhances the efficiency and stability of perovskite solar cells.
• PSCs fabricated with Pc-passivated perovskite films exhibit remarkable stability under high moisture and temperature conditions.