The electronic properties of BaTiO3 perovskite oxides are not completely understood, despite their excellent electro-optical performance and potential for light generation. Particularly, when there is multiple peak formation in the photoluminescence spectra, their origins are not discussed. Their luminescence spectra reveal an unexpected thermodynamic relationship between the core excitonic states and the surface of the BaTiO3. These results give a broad insight into the origins of the emission properties of perovskite oxides. The self-trapped excitons contribution to the broadbands highlights their extrinsic origin. Through spectroscopy techniques and parallel factor analysis (PARAFAC) modeling, we demonstrate that additional broadbands are sensitive to extrinsic defects, type ν-CH3, a product of decomposition of 2-propanol. The presence of C-H bonds shows the dependence with the calcination temperature and the increase of the lattice expansion coefficient until 4.7 × 10-6 K-1 resulting in the contribution to the change of band gap with the temperature ((dEg/dT)P). In this work, we correlated the electronic properties of BaTiO3 with intrinsic and extrinsic defects and elucidated the presence of additional broadbands. This approach differentiates the contributions of excitonic states and surfaces, which is necessary to understand the electronic properties of perovskite oxides.