CaMgSi2O6:Eu2+ thin-film phosphors (TFPs) were grown on sapphire substrates using a simple Pechini-type sol-gel (PSG) deposition technique. After deposition, the 10-layer-coated films (similar to 850 nm thick) were then annealed between 900 and 1150 degrees C for 2 h in a 95% N-2/5% H-2 gas flow. The optical properties, morphology, and crystallographic structures of the CaMgSi2O6:Eu2+ TFPs were characterized. The PSG process produced efficient CaMgSi2O6:Eu2+ TFPs with a pure blue color (x=0.15, y=0.06), a high crystallinity, and a smooth morphology. To enhance photoluminescence (PL) emission, two-dimensional (2D) triangular-lattice SiNx air-hole photonic crystal layers (PCLs) were introduced into the CaMgSi2O6:Eu2+ TFPs using nanosphere lithography. The normally directed PL intensity of the PSG-derived CaMgSi2O6:Eu2+ TFP with a 2D triangular-lattice SiNx air-hole PCL was 11.4 times higher than that of a flat CaMgSi2O6:Eu2+ TFP. The enhanced PL efficiency of the PSG-derived CaMgSi2O6:Eu2+ TFPs was attributed to the combined increase in the extraction of blue emission light and the absorption of UV excitation light through Bragg scattering and the leaky modes produced by the 2D PCLs.