Figure 4
Effect of lens design on the performance of a 3 × 3 1-cell FWPV.
(a). Dependence of lens focal length on the intensity of the edge emission. The intensity was measured using an integral sphere. The results suggested that the lowest optical loss occurred when the rays were focused on the bottom BSR. (b). Simulated and experimental optical efficiencies of FWPVs prepared with various lens designs. As a result of a lower degree of optical loss, the best-designed microstructure (f = 5.0 mm) provided the highest value of ηopt. (c.) Relationship between the intervals of the lenses and the intensity of the top surface emission. A larger interval resulted in higher probability of top losses. (d). Dependence of the lens interval on the optical efficiency. A minimal interval led to the best performance. (e). Photograph of the best-designed FWPV; the rays were clearly focused as spots on the bottom layer.
