Table 1.

Optical wave propagation and photon management mechanisms in solar cells

Feature size	Period ≪ wavelength	Period ≅ wavelength	Period ≫ wavelength
Physical effect	Formation of a refractive index gradient	Diffraction of light	Refraction of light
Description of optical wave propagation	Effective medium theory	Diffraction theory or numerical simulation	Ray or geometric optics
Potential application	Broadband anti-reflection coating	Light trapping in thin-film solar cell	Light trapping in bulk solar cell