Light Coupling and Trapping in Ultrathin Cu(In,Ga)Se2 Solar Cells Using Dielectric Scattering Patterns

Area of Science:

• Materials Science
• Renewable Energy
• Nanotechnology

Background:

• Ultrathin copper indium gallium selenide (CIGSe) solar cells require strategies to improve light absorption and efficiency.
• Nanoscale light scattering patterns offer a potential method for enhancing photovoltaic performance.

Purpose of the Study:

• To demonstrate photocurrent enhancement in ultrathin CIGSe solar cells using nanoscale dielectric light scattering patterns.
• To investigate the impact of front-side and back-interface patterning on light coupling and trapping.

Main Methods:

• Substrate conformal imprint lithography was used to create nanoscale dielectric patterns (TiO2 and SiO2 nanoparticles).
• Fabrication of ultrathin CIGSe solar cells with patterned front surfaces and Mo/CIGSe back interfaces.
• External quantum efficiency measurements and 3D finite-difference time-domain (FDTD) simulations were employed.

Main Results:

• Patterning the front surface with TiO2 nanoparticles slightly enhanced photocurrent across the 400-1200 nm range.
• SiO2 nanoparticle patterning at the Mo/CIGSe back interface increased cell efficiency from 11.1% to 12.3% via enhanced light trapping.
• Nanoparticle inclusion reduced parasitic absorption in the Mo back contact, with further reduction observed in semitransparent CIGSe cells on patterned ITO.

Conclusions:

• Nanoscale dielectric patterning is an effective strategy for enhancing light management in ultrathin CIGSe solar cells.
• Optimizing pattern geometry and exploring semitransparent architectures can further improve device efficiency and reduce losses.