Optical confinement can induce enhancement of the resonance energy transfer between fluorescent molecules by influencing the interaction between the different available energy levels. We study the energy transfer between a pair of molecules, tris(2-phenylpyridine) iridium and bis(2-methyl-8-quinolinato)-4-phenylphenolate aluminum, which are extensively used in organic light-emitting diode technologies. These molecules have previously shown Förster energy transfer. We present the result of the dipolar coupling of these two molecules embedded in a poly(N-vinylcarbazole) film and inserted in a colloidal photonic crystal. Due to the presence of the photonic band gap, the efficiency of the energy transfer has been improved. A thermal study of the emission under the effect of the photonic band gap has been performed.