Enhancement of solar cell efficiency by spectral-conversion using rare earth-metal nanoclusters

A novel organic/inorganic nanocomposite is proposed as a luminescent material of a spectral converter (SC) for improving the energy conversion efficiency of solar cells. The nanocomposite consists of a polymer matrix doped with rare earth-centered heterometallic alkoxides, rare earth (RE)-metal (M) nanocluster. The excitation edge of Eu3+ was found to be extended from about 400 nm to 470 nm by adding Michler's ketone to the nanocomposite. The broadening of the excitation wavelength range enhanced the energy conversion efficiency of a single-crystalline Si solar cell by 9.9%. Also it was found that Eu-M nanocluster can emit broad-band luminescence ranging from 400 nm to 600 nm in addition to the narrow-bands luminescence peculiar to Eu3+ when M is selected. Such controllability in both excitation and emission spectra could make it possible to use the nanocomposite doped with RE-M nanocluster as a luminescent material for SCs for various solar cells having different spectral responses.