Scalar scattering model of highly textured transparent conducting oxide

Abstract

Amorphous silicon solar cell is one of the most well developed solar energy solutions. In order to increase the energy conversion efficiency, light-trapping is necessary to the cell structure. Light trapping can be achieved by a textured transparent conducting oxide ͑TCO͒ layer and one of the critical factors of textured TCO is its haze value, which characterizes the scattering capability of the TCO. Recently several highly textured TCOs were presented with high haze at near IR region, where the haze of textured interfaces traditionally suffered from reduced scattering. However, suitable modeling is not established yet. In this work, we use scalar scattering theory and Kirchhoff approximation to solve haze value of complex surfaces analytically. Different from original Rayleigh scattering expression, this model illustrates intricacy between the surface roughness, correlation length, and the separation between different groups of height distributions. The resulting analytical formulation can be applied successfully not only in regular monotonically decaying spectral hazes but also various nonmonotonically shaped ones, meanwhile it retains important physical factors which can be useful for process evaluation.

Surface-properties relationship in sputtered Ag thin films: Influence of the thickness and the annealing temperature in nitrogen

“…It is known that the main surface coefficients for the vertical and lateral dimensions ( and L) are connected to the coherent and incoherent components of the total reflectance, which can be written as [36]: R C = R 0 exp{−(4 / ) 2 } and R I = (R 0 − R C ) [1 − exp{−( L/ ) 2 }], where R 0 is the reflectance at normal incidence when the surface approaches perfect flatness. Then, the haze parameter expressed as H R = R I /(R C + R I ) depends on the surface roughness and the correlation length values in addition to the light wavelength.…”

Organic-acid texturing of transparent electrodes toward broadband light trapping in thin-film solar cells

“…2(a)), the craters can be characterized by vertical roughness and lateral correlation length (lateral roughness) [30,31]. The vertical roughness σ rms is given as follows:…”

“…1(d) and (e). Modified scalar scattering theory by coupling between photon and rough interface is used to understand the lightscattering performance as a function of vertical roughness (σ rms ) and lateral correlation length (a corr ) [30]: …”

Optical Absorption Enhancement in Amorphous Silicon Films and Solar Cell Precursors Using the Aluminum-Induced Glass Texturing Method

“…The TCO film is either textured after its deposition or self-textured during deposition due to the specifics of the deposition process. The scattering properties of a number of differently textured surfaces have been studied in the literature, and the optical haze value has been widely used as a parameter to evaluate the scattering of light within thin-film structures [3,7,8]. It is well known that front surface texturing, which leads to scattering of light, and a good back surface reflector are both needed to gain the full benefit of optical absorption enhancement.…”