Intensity enhancement in textured optical sheets for solar cells

We adopt a statistical mechanical approach toward the optics of textured and inhomogeneous optical sheets. As a general rule, the local light intensity in such a medium will tend to be <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2 n^{2}(x)</tex> times greater than the externally incident light intensity, where <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n(x)</tex> is the local index of refraction in the sheet. This enhancement can contribute toward a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4 n^{2}(x)</tex> increase in the effective absorption of indirect-gap semiconductors like crystalline silicon.