Current Concepts for Optical Path Enhancement in Solar Cells

Abstract

The conversion efficiency of a solar cell is directly connected to the number of photons absorbed in the absorber material of the cell. Therefore, it is of critical importance to insert as many photons as possible into the cell and keep them inside the cell until they are finally absorbed. While achieving the first aspect is referred to as antireflection, the second aspect is commonly called optical path enhancement, also known as light Trapping, which is the focus of this chapter. Light trapping in commercially available c-Si solar cells utilizes approaches that are based on ray optics. A common approach to achieve real light trapping is to change the propagation direction of the light such that total internal reflection occurs. A very effective light trapping concept is the full randomization of the propagation directions of the incident sunlight after hitting the first absorber interface

Mean path length inside nonscattering refractive objects

“…Path length distributions and mean path length are central to the design of many optical systems where a ray optics description can be used. They can be used for calculating the optical properties of absorbing and scattering media [6,7], refractive granular media in pharmaceutical powders [8], for solar cell design [9][10][11], random lasing [12], and integrating spheres [13,14]. Ray tracing can also be combined with diffraction effects to calculate the electromagnetic scattering properties of large particles in models such as the geometric optics approximation and physical optics model [15][16][17][18][19][20], or anomalous diffraction theory [21][22][23].…”

On KCN treatment effects on optical properties of Si-based bilayers

“…In thin film solar cells the optical path length enhancement connected with the so-called light trapping is highly required and various effective concepts have been applied so far [17]. The only but deficient enhancements of Λ were achieved for the KCN MeOH treated bilayer B (+∆Λ in Table 2).…”

Plasmonic Light-Management Interfaces by Polyol-Synthesized Silver Nanoparticles for Industrial Scale Silicon Solar Cells

“…However, the typical surface coverages attained by this strategy lie between 25% to 35% . This value being significantly larger than 10% (an optimum value for Ag and Au nanoparticles) casts detrimental effects on cell performance as parasitic absorption that jeopardizes their use as ideal means of optimum light management. − …”