Optical efficiencies for Luminescent Solar Concentrators (LSC) based on thin films of Polymethylmethacrylate (PMMA) doped by luminescent dye BASF-241 deposited on PMMA transparent plates are measured and calculated. The influence of refractive index of optical matching material on LSC performance is analyzed. A comparison of emission anisotropy with quantum yield and self-absorption leads to optimalization of thickness and optical density of the thin doped films. Enhancement of luminescence of Rhodamine 6G (Rh6G) in the presence of silver aggregates is reported.