Optical Coupling Sensitivity Study of Luminescent PV Devices Using Monte Carlo Ray-Tracing Model

Abstract

The optimization of optical coupling between photovoltaic (PV) solar cells and luminescent devices such as luminescent solar concentrators (LSC) and luminescent downshifting (LDS) layers is important and can affect their performance significantly. An LSC of 60 {\texttimes} 60 {\texttimes} 3 mm and LDS of 100 {\texttimes} 100 {\texttimes} 0.01 mm both doped with CdSe/ZnS quantum dots (QDs) and coupled to PV solar cells have been modelled. The performance and optical coupling sensitivity of these luminescent PV (LPV) devices were studied by changing the air gap thickness (G) between the luminescent layer and PV solar cell using a Monte Carlo Ray-Tracing (MCRT) algorithm. The host materials were epoxy and poly (methyl methacrylate) (PMMA) polymers for the LSC and LDS, respectively, with a refractive index of 1.5. LPV devices were irradiated by standard AM1.5 global solar radiation. The highest optical efficiency and solar concentration ratio obtained for the LSC device were 2.8% and 56% respectively. Both were decreased to 2.2% and 43% when G was increased from 0 to 0.5 mm. For G = 0.5--2 mm, the optical efficiency and solar concentration ratio decreased to 1.85% and 36%, respectively. In the LDS device, an optical efficiency of 82% was achieved when there was no air gap between the luminescent device and the PV solar cell. Efficiency dropped to 76% when G increased to 0.1 mm and further decreased to 66% for G = 2 mm. The total performance deduction ($Δ$P) was respectively 37% and 19% for LSC and LDS when G increased from 0 to 2 mm which showed that the LSC was more sensitive than the LDS to optical coupling.