Intensity Modulated Photocurrent Microspectrosopy for Next Generation Photovoltaics

Area of Science:

• Materials Science
• Photovoltaics
• Spectroscopy

Background:

• Understanding spatial variations in solar cell performance is crucial for improving efficiency and longevity.
• Traditional methods often lack the spatial resolution to pinpoint localized degradation or performance differences.
• Intensity Modulated Photocurrent Spectroscopy (IMPS) provides frequency-domain information about charge carrier dynamics.

Purpose of the Study:

• To describe a novel microscopy-based Intensity Modulated Photocurrent Spectroscopy (IMPS) system capable of imaging.
• To apply this imaging IMPS method to study degradation in back-contact perovskite solar cells.
• To correlate spatially resolved optoelectronic responses with specific material properties or interfaces.

Main Methods:

• Adaptation of a large-area laser beam induced current microscope for imaging IMPS.
• Application of the microscopy-based IMPS to analyze back-contact perovskite solar cells.
• Modeling the IMPS response using a diffusion-recombination model, including lateral diffusion for back-contact cells.

Main Results:

• The imaging IMPS system successfully differentiated areas with distinct frequency responses in degraded perovskite cells.
• Spatial maps of carrier ambipolar diffusion length were calculated in the low-frequency limit.
• The study demonstrated the capability to correlate localized optoelectronic behavior with specific cell regions.

Conclusions:

• Microscopy-based IMPS offers high spatial resolution for analyzing frequency-domain optoelectronic responses in solar cells.
• This technique is effective in identifying and characterizing degradation in perovskite solar cells.
• The developed model and imaging approach provide valuable insights into charge transport and recombination mechanisms.