<p>Graphitic carbon nitride (g-C₃N₄) is a polymeric semiconductor composed of carbon and nitrogen atoms. It has a layered structure similar to graphite, with strong in-plane covalent bonds and weak van der Waals forces between layers with a <b>c</b>onjugated π-system which enables delocalization of the π-electrons, crucial for optical and electronic properties. On the other hand, LuAG: Ce³⁺ and YAG: Ce³⁺ are phosphors well known with their effective green and yellow luminescence. In this study, we investigated spectral behavior of Ce³⁺-activated green and yellow phosphors of LuAG: Ce³⁺ and YAG: Ce³⁺ along with the g-C₃N₄ in an optically transparent polymethylmethacrylate (PMMA) matrix. When we used these two substances in the critical concentration, we measured 65 and 88% enhanced emission for the green and yellow phosphors, respectively. The presence of graphitic carbon nitride in the binary phosphor g-C₃N₄ blends resulted in red shifts of 28 and 32&#xa0;nm for the emission maxima of LuAG: Ce³⁺ and YAG: Ce³⁺, respectively. In the case of 6-layer, ~ 60&#xa0;μm thick, spin-coated films, an increase in emission intensity of up to 200% and a red shift of about 70&#xa0;nm were observed for both phosphors. The reasons for this spectral enhancement are explored in detail on the basis of excitation and emission spectra as well as excited state lifetime measurements performed on nanosecond and microsecond time scales, respectively. Experimental evidence for a potential energy transfer from g-C₃N₄ to phosphors is presented. The preliminary results of the studies indicate that the binary mixtures of g-C₃N₄ and phosphor prepared at correct concentrations could be promising materials for LEDs, car headlights and display technologies.</p>