Luminescent solar concentrators. I. Concentrators based on mixtures of dyes in PMMA. Spectral and luminescent properties, reabsorption and energy transfer

Spectral and luminescent properties of efficient and stable commercial organic dyes in solutions and polymethylmetacrilate (PMMA), absorbing and emitting in wavelength ranges 300-680 nm and 390-750 nm, respectively, are investigated. Using different excitation and registration schemes, it is demonstrated that spectral shifts of initial radiation caused by reabsorption are observed at wavelengths around 1.5 cm. The process of excitation energy transfer from the UV range to the red range of the spectrum is investigated in mixtures of 4-6 dyes of different compositions. The maximum efficiency of radiation transfer from 300 nm to 560-580 nm, exceeding the efficiency of individual fluorophores by a factor of >1.6 is obtained for mixtures of four dyes POPOP(bis-MSB)-Coumarin 30-DCM-Pyrromethene 580 (Rhodamine 11B) in PMMA.