Light trapping in ultrathin plasmonic solar cells

Area of Science:

• Materials Science
• Nanotechnology
• Renewable Energy

Background:

• Ultrathin solar cells offer potential for flexible and low-cost energy generation.
• Enhancing light absorption in the active layer is crucial for improving solar cell efficiency.
• Plasmonic nanostructures can manipulate light and enhance absorption in thin films.

Purpose of the Study:

• To design, fabricate, and measure ultrathin hydrogenated amorphous silicon (a-Si:H) solar cells.
• To investigate the effect of nanostructured plasmonic back contacts on photocurrent.
• To confirm the mechanism of photocurrent enhancement using experimental and simulation methods.

Main Methods:

• Fabrication of ultrathin a-Si:H solar cells with nanostructured plasmonic back contacts.
• Angle-resolved photocurrent spectroscopy to analyze spectral response.
• Full-field electromagnetic simulations to model light absorption.

Main Results:

• Nanostructured plasmonic back contacts significantly enhance short-circuit current densities compared to flat or random contacts.
• Primary photocurrent enhancement observed in the 550 nm to 800 nm spectral range.
• Experimental results show good agreement with electromagnetic simulations, confirming guided mode coupling.

Conclusions:

• Nanostructured plasmonic back contacts are effective for enhancing light absorption and photocurrent in ultrathin a-Si:H solar cells.
• The observed enhancement is attributed to coupling of light to guided modes within the cell.
• This study provides a basis for designing optimized nanostructured back reflectors for thin-film solar cells.