Separating charge carriers in low-mobility materials presents a considerable challenge for organic photovoltaic devices. This study addresses this issue by producing CoFe \(_2\) O \(_4\) nanoparticles via the proteic sol–gel method and incorporating them into the heterojunction mixture of regioregular poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C \(_{61}\) -butyric acid methyl ester (PCBM) at a concentration of 7%. The addition of these nanoparticles led to a suppression of photoluminescence, indicating that the thin films were successfully decorated with magnetic ferrite nanoparticles (NPs). Our analysis demonstrated that incorporating NPs into the bulk heterojunction (BHJ) of P3HT:PCBM blends resulted in a notable reduction in photoluminescence compared to films without decoration. This suppression suggests an increase in the density of free charge carriers and a decrease in recombination events. Moreover, atomic force microscopy revealed a higher transverse current in the BHJ:NP film when compared to both the BHJ and P3HT films without NPs. This increase implies that the nanoparticles may serve as nucleation centers for forming conductive pathways, thereby facilitating charge transport within the film. Consequently, the presence of nanoparticles can enhance the interfacial area between the film materials, promoting improved charge transfer and reducing the recombination of charge carriers.
