The data sets stored here accompany the related research article, showing details of spectroscopic investigations. The opj. file contains spectroscopic data for four figures in manuscript. The file can be opened by Origin. Figure 1 contains absorption spectra from blended film of lanthanide nanoparticles and organic semiconductors (tetracene and rubrene). Figure 2 contains transient absorption spectra of molecules-lanthanide nanoparticles solution. Figure 3 contains steady state photoluminescence spectra of samples. Figure 4 contains upconversion spectra of Yb-doped nanoparticles with organic semiconductors. The data for Figure 4d is plotted by integrated emission intensity as a function of measurement temperature. The dataset for figure 4e includes quantum yield values measured under different excitation power densities and different temperatures.