Understanding the Energy Band Mechanism in MoS2/Co3O4 Heterojunction-Based Bioplastics Affected by Carrier Concentration

Bioplastics are adopted to replace fossil-based plastics because they are microplastic-free and self-degradable without releasing greenhouse gasses. Despite having many benefits, the main applications of bioplastics are packaging and kitchenware. Moreover, the utilization of bioplastics in electronic applications is still underexplored. Consequently, the development of bioplastics for electronic applications, especially heterojunctions, is essential. Here, we report a novel molybdenum disulfide (MoS₂)/cobalt oxide (Co₃O₄) heterojunction based on bioplastic semiconductors, with agar as a matrix. This work also exposes the effect of carrier concentration on the mechanism of an energy band. Using the density of state in three dimensions, Anderson's rule, and the Fermi energy level calculated by carrier concentration, we find that the energy gaps of the MoS₂/Co₃O₄ heterojunction at various concentrations almost match the energy gap evaluated by Tauc's relation. Additionally, leveraging the MoS₂/Co₃O₄ heterojunction as a photodetector, the optimized device indicates an ideality factor of 1.59, a response time of 127 ms, and a recovery time of 115 ms. Our work not only represents a significant step towards using bioplastics in electronic applications but also reveals the mechanism of the energy band affected by carrier concentration.