Stable and efficient perovskite solar cells via hydrogen bonding and coordination

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• Perovskite solar cells (PSCs) suffer from instability due to ion migration, degrading device performance.
• Ion migration and accumulation in the perovskite layer negatively impact device efficiency and longevity.

Purpose of the Study:

• To enhance the efficiency and stability of PSCs by introducing a novel n-type, low optical gap-conjugated organic molecule.
• To broaden the near-infrared spectral response of PSCs and suppress ion migration.

Main Methods:

• Incorporation of COTIC-4F (or COTIC-4Cl) into the perovskite precursor solution.
• Characterization studies including X-ray diffraction, UV-Vis spectroscopy, and device performance testing.
• Passivation of lead (Pb) traps using the carbonyl group of the organic molecule.

Main Results:

• COTIC-4F forms hydrogen bonds with perovskites, enhancing MA+ anchoring and suppressing ion migration.
• Organic molecules passivate Pb traps, reducing carrier recombination and improving film morphology.
• COTIC-4F facilitated greater charge transfer than COTIC-4Cl, leading to enhanced photocurrent and a maximum power conversion efficiency of 21.72%.

Conclusions:

• The introduction of COTIC-4F significantly improves PSC efficiency, fill factor (82.02%), and long-term stability.
• COTIC-4F is a promising additive for developing stable and high-performance perovskite solar cells.
• Suppression of ion migration and trap passivation are key strategies for advancing PSC technology.