Improvement of light trapping in thin-film silicon solar cells by combining periodic and random interfaces

The concept of photonic random textures for application as a light-trapping scheme in thin-film solar cells is introduced. Those textures consist of a randomly textured interface, as commonly applied in thin-film solar cells, which is superimposed with a two-dimensional grating structure. The light-scattering properties of those textures are investigated by scalar scattering theory for transmission into the absorber layer and reflection at the back contact. A quantity to describe the light-trapping efficiency is derived and verified by rigorous diffraction theory. The photonic random textures outperform the random textures and the grating structures significantly. PACS Nos.: 42.25.Dd, 42.79.Dj, 88.40.fc. Nous introduisons le concept de texture photonique aleatoire dans le schema de captation de la lumiere dans les cellules minces photovoltaiques. Ces textures nouveau genre consistent en une interface texturee aleatoirement, frequemment utilisee en cellules minces photovoltaiques, superposee a un reseau de diffraction 2D. Nous utilisons la theorie scalaire de la diffraction pour etudier les proprietes de diffusion de la lumiere par ces textures pour la transmission vers la couche absorbante et la reflexion arriere. Nous utilisons la theorie rigoureuse de la diffraction pour evaluer et verifier une quantite qui decrit l'efficacite de captation de la lumiere. Les textures photoniques aleatoires surpassent les textures aleatoires et les reseaux de diffraction de facon significative. [Traduit par la Redaction]
Introduction Light trapping in silicon-based thin-film solar cells is an important issue, because the absorption near the band gap is quite low for flat devices [1,2] and the device thickness [...]