Light Trapping Transparent Electrodes with a Wide-Angle Response

The angle dependent transmission of light trapping transparent electrodes is investigated. The electrodes consist of triangular metallic wire arrays embedded in a dielectric cover layer. Normal incidence illumination of the structure produces light trapping via total internal reflection, virtually eliminating all shadowing losses. It is found that varying the external angle of incidence can affect the light trapping efficiency ηLT due to partial loss of internal reflection and increased interaction with neighboring wires. Despite these effects, a judicious selection of geometry and materials can reduce shadowing losses by more than 85% over a surprisingly large angular range of 120°. It is demonstrated that the angle-averaged shadowing losses in an encapsulated silicon solar cell under illumination with unpolarized light can be reduced by more than a factor of two for incident angles between −60° and +60° off-normal across the entire AM1.5 solar spectrum.