Improved Photon Absorption in a-Si:H Solar Cells using Photonic Crystal Architectures

摘要

Improved light-trapping is a major route to improving solar cell efficiencies. We design a combination of a 2-dimensional photonic crystal and a one-dimensional distributed Bragg reflector as the back reflector for a-Si:H solar cells. This configuration avoids inherent losses associated with textured back-reflectors. The photonic crystals are composed of ITO and can easily serve as a conducting back contact. We have optimized the geometry of the photonic crystal to maximize absorption using rigorous scattering matrix simulations. The photonic crystal provides strong diffraction of red and near-IR wavelengths within the absorber layer and can enhance the absorption by more than a factor of 10 relative to the case without the photonic crystal. The optical path length with the photonic crystal can improve over the limit for a random roughened scattering surface.