We report a systematic study of the strain effect on thin films of nonsuperconducting PrBa 2 Cu 3 O 7 - δ produced by pulsed laser deposition. The transport properties and the Raman active modes are studied for high-quality PrBa 2 Cu 3 O 7 - δ thin films grown on SrTiO 3 (100) under a tensile strain, and under a compression strain on LaSrAlO 4 (001) substrate. The data show a lowering of the polaron binding energy for the samples under compressive strain, as the film thickness decreases. This can be directly concluded from the behavior of the Raman active modes. These modes show a shift of the stretching modes, shifted to lower wave number (cm - 1 ) under the tensile strain, and to higher wave number, under compressive strain. Our results are analyzed in terms of the Fehrenbacher and Rice-model.