Flexible photodetector with fast response based on bioplastic semiconductor as ZnO/NiO heterojunction

Zinc oxide (ZnO) and nickel oxide (NiO) heterojunctions have been widely studied and applied in various applications due to their electrical properties and wide band gap. However, the conventional deposition process of ZnO/NiO heterojunction is complex, requiring high temperatures and a vacuum. Additionally, ZnO/NiO heterojunctions are typically deposited on solid substrates, which limits their use in flexible electronics. This study presents a simple and efficient method for the synthesis and fabrication of a flexible ZnO/NiO bioplastic as a photodetector. The ZnO and NiO nanoparticles are synthesized using a precipitation method. Simultaneously, flexible ZnO/NiO bioplastics are fabricated using the gel-casting method, with agar serving as the matrix and nanoparticles as fillers. We observe that increasing the concentration of both nanoparticles enhances the electrical properties and reduces the band gap of ZnO/NiO bioplastic. By utilizing flexible ZnO/NiO bioplastic as a photodetector, the optimized devices have an ideality factor, response time, and recovery time of 1.67, 55 ms, and 34 ms, respectively. Moreover, the change in photocurrent density remains consistent at different bending angles. This research offers not only a mechanism for engineering the band gap of heterojunction but also opens a new opportunity for bioplastic semiconductors in flexible electronic applications.