Single-Crystal Perovskite Solar Cells Exhibit Close to Half A Millimeter Electron-Diffusion Length

Area of Science:

• Materials Science
• Solid-State Physics
• Photovoltaics

Background:

• Single-crystal halide perovskites offer high carrier mobility and long lifetimes, ideal for thick semiconductor applications.
• Thick perovskite layers typically suffer from poor charge collection, necessitating high external bias, leading to dark current and degradation.
• Extending carrier diffusion length is crucial for overcoming limitations in thick perovskite devices.

Purpose of the Study:

• To fabricate thick single-crystal perovskite solar cells with enhanced charge collection efficiency.
• To investigate the impact of increased thickness on the performance of perovskite solar cells.
• To demonstrate the potential of long carrier diffusion lengths in enabling thick perovskite optoelectronic devices.

Main Methods:

• Fabrication of single-crystal perovskite solar cells with thicknesses up to 290 µm.
• Measurement of power conversion efficiencies (PCEs) for varying cell thicknesses.
• Estimation of electron-diffusion length using thickness-dependent short-circuit current measurements.

Main Results:

• Successfully fabricated perovskite solar cells up to 400 times thicker than conventional films.
• Achieved high charge-collection efficiency in thick cells without external bias.
• Recorded PCEs of 20.0%, 18.4%, and 14.7% for 110, 214, and 290 µm thick cells, respectively.
• Estimated electron-diffusion length of approximately 0.45 mm under 1 sun illumination.

Conclusions:

• Long electron-diffusion length in single-crystal perovskites enables high efficiency in thick devices.
• Overcoming charge collection issues in thick perovskites is achievable, paving the way for new applications.
• These findings support the use of perovskite devices in optoelectronics requiring substantial active layer thickness.