Electrostatic Shielding to Stabilize Buried Interface Toward High-Performance Inorganic Perovskite Solar Cells

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• Halide migration is a key factor limiting the operational stability of inorganic perovskite solar cells.
• High temperatures can induce non-photovoltaic phase transitions in perovskite films due to iodine diffusion into the hole transport layer (P3HT) via electrostatic interactions.

Purpose of the Study:

• To investigate a charge depolarization strategy to mitigate halide migration and improve the stability and efficiency of inorganic perovskite solar cells.
• To explore the effect of incorporating Chevrel phase Mo6S8 nanosheets into P3HT on device performance.

Main Methods:

• A charge depolarization strategy was implemented by incorporating Chevrel phase Mo6S8 nanosheets into the Poly(3-hexylthiophene-2,5-diyl) (P3HT) hole transport layer.
• The covalent coupling between Mo6S8 and P3HT was analyzed for its effect on interfacial charge distribution and electrostatic attraction to iodine ions.
• Perovskite solar cell devices with the structure FTO/TiO2/CsPbI2.95Br0.05/P3HT/Ag were fabricated and tested.

Main Results:

• Incorporation of Mo6S8 nanosheets effectively suppressed positive potential sites in P3HT, reducing iodine ion attraction and preventing phase transitions.
• Charge transfer through the S─Mo bond promoted P3HT oxidized states and rearranged energy alignment, enhancing charge collection.
• The power conversion efficiency (PCE) of the perovskite solar cells improved from 18.43% to 20.46% with Mo6S8 incorporation.
• The devices exhibited remarkable stability, retaining 93% efficiency after 5280 hours in ambient air and 95% after 989 hours at 85 °C.

Conclusions:

• The charge depolarization strategy using Mo6S8 nanosheets is effective in suppressing halide migration and enhancing the stability of inorganic perovskite solar cells.
• The developed devices show promising long-term operational stability under various environmental conditions, making them suitable for practical applications.
• This approach offers a viable pathway for developing highly efficient and durable perovskite solar cell technologies.