Reducing Surface Halide Deficiency for Efficient and Stable Iodide-Based Perovskite Solar Cells.

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• Perovskite solar cells (PSCs) require high iodine content for small bandgaps.
• Iodine vacancies on perovskite surfaces cause defects, recombination, and hysteresis, limiting PSC performance.
• Thermal annealing can lead to iodine evaporation and surface defects.

Purpose of the Study:

• To mitigate surface iodine deficiency and associated defects in perovskite films.
• To enhance the efficiency and operational stability of perovskite solar cells.
• To explore cadmium iodide (CdI2) as a surface modification agent for perovskites.

Main Methods:

• Surface treatment of perovskite films using cadmium iodide (CdI2).
• Characterization of perovskite film surface iodine content and defect levels.
• Fabrication and performance testing of modified perovskite solar cells (PSCs).
• Operational stability testing under constant illumination.

Main Results:

• CdI2 treatment effectively reduced surface iodine deficiency and stabilized iodine ions.
• Interfacial charge recombination losses were significantly reduced.
• Blade-coated PSCs achieved a high efficiency of 21.9% with a 1.20 V open-circuit voltage and a 0.31 V voltage deficit.
• Modified PSCs retained 92% of their initial efficiency after 1000 hours of continuous illumination.

Conclusions:

• CdI2 surface modification is a promising strategy for optimizing perovskite optoelectronic properties.
• This approach leads to more efficient and stable perovskite solar cells.
• The findings offer a pathway for improved performance in PSCs and other optoelectronic devices.