Herein, magnetic Fe3O4@SiO2 nanomaterial functionalized with amine groups (Fe3O4@SiO2@IPA) doped with manganese (Mn) was prepared, characterized and used for solar cell application. Fe3O4@SiO2@IPA-Mn was prepared via the co-precipitation and sol-gel techniques. Energy-dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) measurements were performed to examine the structure of Fe3O4, Fe3O4@SiO2, Fe3O4@SiO2@IPA and Fe3O4@SiO2@IPA-Mn. General morphology and textural properties of the prepared magnetic nanomaterials were clarified by Brunauer-Emmett-Teller (BET) and scanning electron microscopy (SEM). In addition, Ultraviolet-visible (UV-Vis) spectroscopy and thermal gravimetric analysis (TGA) were used to have a knowledge about the energy band gap and thermal behavior of the prepared magnetic nanomaterials. The energy band gap of Fe3O4@SiO2@IPA with spinel structure was determined as approximately 2.48 eV. It was understood that Fe3O4, Fe3O4@SiO2 and Fe3O4@SiO2@IPA showed type IV-H3 hysteresis cycle according to IUPAC. From the BET data, it was determined that the specific surface areas of Fe3O4, Fe3O4@SiO2 and Fe3O4@SiO2@IPA were 60.85, 28.99 and 40.41 m(2)/g, respectively. The pore size distributions of Fe3O4, Fe3O4@SiO2 and Fe3O4@SiO2@IPA were calculated as 8.55, 1.53 and 1.70 nm, respectively, by the BJH method. Also, it was observed that the dominant pore widths of Fe3O4, Fe3O4@SiO2 and Fe3O4@SiO2@IPA were calculated similar to 5.58, similar to 0.88 and similar to 17.92 nm, respectively, by the DFT method. Au/CuO/Fe3O4@SiO2@IPA-Mn/ZnO/SnO2: F solar cell device was created using existing Fe3O4@SiO2@IPA-Mn as a buffer layer. The power conversion efficiency (%) of Fe3O4@SiO2@IPA-Mn based solar cell device was calculated as 2.054. This finding suggest that Fe3O4@SiO2@IPA-Mn can be used as a promising sensitizer in solar cell technology. Moreover, in this study, the effectiveness of the modification of manganese (one of the transition metals, which is cheap and easily available) with magnetic nanomaterials in the use of solar cell technology was demonstrated for the first time.