Downshifting maximization procedure applied to [Eu(bphen)(tta)3] at different concentrations applied to a photovoltaic device and covered with a hemispherical reflector

In this work we propose the determination of the maximum downshifting efficiency of any new downshifter applied to photovoltaic (PV) devices in terms of downshifter concentration and the description of the optics applied as the standard procedure if increases in EQE, conversion efficiency and/or Isc are being reported. A standard procedure is defined for determining the maximum downshifting efficiency, firstly in by reaching the solubility limit of the downshifting precursors and, subsequently, by reaching the maximum luminescent intensity of the downshifter. Also, we consider that a description of the optics applied to the experiment should be included to guarantee the reproducibility of the results. This procedure is successfully applied to poly(methylmethacrilate) (PMMA) films containing the active species [Eu(bphen)(tta)3] (bphen = 4,7-biphenyl-1,10-phenantroline and Htta = thenoltrifluoroacetone). Finally, a hemispherical reflector is applied on the PV device in order to modify the optics applied in the experimental setup and for increasing the EQE of the PV device. This scheme is proposed to be integrated in PV devices for its use in niche applications where concentrator photovoltaics (CPV) offers some advantages in relation to non-concentrator configurations.