Engineering Absorption in CdSe/CdS Nanostructures Through Controlled Strain and Dimensionality

ABSTRACT This study theoretically investigates the optical absorption spectrum of CdSe/CdS core–shell quantum dots (CSQDs) under the combined influence of quantum confinement, elastic strain, and an on‐center donor impurity. Utilizing the effective mass approximation and continuum elasticity theory, we model the system's energy eigenvalues and absorption coefficients. For unstrained CSQDs, our findings demonstrate that quantum confinement strongly dictates the electronic energy levels and absorption peak positions, exhibiting a blueshift with decreasing core radius and a redshift with increasing shell thickness. Crucially, the presence of elastic strain, originating from the lattice mismatch between the core and shell materials, significantly modifies the confinement potential. This strain leads to a progressive delocalization of electron wavefunctions into the shell material, particularly for higher excited states, effectively attenuating the confinement potential. This wavefunction redistribution directly impacts the energy level spacing and causes concomitant redshifts in the absorption spectra with increasing core size. Our results provide fundamental insights into how strain and dimensionality can be precisely engineered to tune the optoelectronic properties of CdSe/CdS nanostructures, offering a pathway for designing advanced optoelectronic devices.