Engineering 2D Zincblende CdS: Unlocking the Potential for the Next-Generation Tunable Spintronic and Optoelectronics

The ability to engineer and tune/tailor the electronic structure of semiconductors using external stimuli in a controlled fashion is pivotal to the progress of adaptive optoelectronic and spintronics technologies. However, insight into how an applied electric field and mechanical strain modulate the electronic bandgap, orbital hybridization, and optical response in zincblende CdS remains unresolved. Herein, through first-principles calculations, we conclusively reveal the stimulus-driven modulation of the electronic bandgap in CdS throughout a wide energy window. The application of electric fields and mechanical strain enables precise modulation: positive electric fields decrease the bandgap from 0.96 eV to 0.44 eV, while negative fields increase it from 1.24 eV to 1.70 eV. Furthermore, biaxial compressive strain increases the bandgap from 1.26 eV to 1.4 eV, whereas tensile strain reduces it from 1.05 eV to 0.75 eV. These intrinsic and extrinsic stimuli induce polarization and alter charge carrier distribution, leading to the switchable dynamics driven predominantly by the Stark effect and influenced by electron–electron interactions and Mott transitions. This modulation affects the orbital states, specifically the Cd (1s, 3d) and S (p) orbitals in the valence band and the Cd (2p) and S (2p) orbitals in the conduction band. Subsequently, controlled changes occur in the partial density of states (PDOS), charge density difference (Δρ) distribution, and local density of states, allowing for the precise control of light interactions. The correlated controlled evolution of electronic and optical properties induced by the applied stimulus reveals dynamically tunable plasmonic and screening behavior, establishing zincblende CdS as a promising candidate for future controlled miniaturized optoelectronic and spintronic technologies.