Inverted organic solar cells enhanced by grating-coupled surface plasmons and waveguide modes

Area of Science:

• Materials Science
• Nanotechnology
• Renewable Energy

Background:

• Organic thin-film solar cells (OTSCs) offer potential for low-cost, flexible photovoltaic applications.
• Enhancing light absorption and charge carrier generation is crucial for improving OTSC performance.
• Plasmonic nanostructures can enhance light scattering and absorption in solar cells.

Purpose of the Study:

• To improve photovoltaic properties in inverted organic thin-film solar cells.
• To investigate the simultaneous excitation of grating-coupled surface plasmons and waveguide modes.
• To enhance light-matter interactions within the active layer of the solar cell.

Main Methods:

• Fabrication of inverted organic solar cells with a gold grating structure on the rear electrode.
• Utilized nanoimprinting with a PDMS stamp (derived from a DVD-R template) to create gratings on the poly(3-hexylthiophene-2,5-diyl):phenyl-C61-butyric acid methyl ester (P3HT:PCBM) layer.
• Characterized optical properties using reflectivity measurements with p- and s-polarized light and measured incident photon-to-current efficiency (IPCE).

Main Results:

• Simultaneous excitation of surface plasmons and waveguide modes was confirmed via reflectivity measurements.
• IPCE measurements showed enhanced photocurrents at wavelengths corresponding to plasmon and waveguide mode excitations.
• Grating-structured solar cells demonstrated an 11% improvement in short-circuit photocurrent and a 16% increase in overall power conversion efficiency.

Conclusions:

• Simultaneous excitation of surface plasmons and waveguide modes is an effective strategy for enhancing OTSC performance.
• The nanoimprinted grating structure significantly boosts light absorption and charge generation in the P3HT:PCBM active layer.
• This approach offers a promising route for developing more efficient and cost-effective organic solar cells.