Probing Hole-State Splitting and Relaxation in Gradient Alloyed CdSe Core–Shell Quantum Dots Using Two-Dimensional Electronic Spectroscopy

excitons. These findings suggest that the gradient alloyed shells on CdSe quantum dots cause symmetry breaking, which results in the light-hole and heavy-hole states splitting. Furthermore, ultrafast (<1 ps) relaxation processes via hole cooling across these three hole states are observed. The hole-state splitting provides a spectroscopic basis for the observed cooling dynamics and may serve as a contributing factor to the enhancement of photoluminescence and optical gain, offering a potential pathway for optimizing excitonic structure in next-generation QD-based optoelectronic devices.