Thulium (Tm) doped aluminum nitride (AlN) thin films are deposited by radio frequency (RF) magnetron sputtering in a pure nitrogen atmosphere. As-deposited thin films are irradiated at room temperature with 335 keV protons and a fluence of 1 × 1014 ions/cm2. The effects of irradiation on the structural and optical properties of the deposited thin films are investigated. Rutherford backscattering (RBS) is performed to determine the thickness and stoichiometric properties of the films while the structural properties of the material before and after irradiation are investigated with x-ray diffraction (XRD). Non-ionizing energy loss (NIEL) study demonstrates that scattering events increase as the ions penetrate deep into the matrix and result in higher damage in the material. Fourier transform infrared spectroscopy (FTIR) is used to see the absorption spectra of thin films which reveals that the implanted films have great capabilities of solar energy storage. Bandgap of the film is determined using diffused reflection spectroscopy (DRS) technique, where a slight upwards shift in bandgap is observed due to irradiation induced material damages.