Signature of Interdot Electronic Coupling from Photoelectron Spectra of Quantum Dot Molecules

The research focuses on examining the electronic coupling between quantum dots in quantum dot molecules. The study involves calculating and analyzing the photoelectron spectra to understand the dot-to-dot interaction in these systems. The interaction between quantum dots can result in unique electronic and optical properties, with electron tunneling playing a significant role. The photoelectron spectra of PbS-PbS, PbS-CdS, and CdS-CdS systems were analyzed using an electron-propagator approach and Dyson equation within the 2nd-order approximation. The results of this study indicate that the primary photoelectron spectral line demonstrates splitting, which is strongly influenced by the separation between quantum dot molecules. Theoretical analysis revealed that the two lowest occupied molecular orbital states exhibit significant differences in their light-matter coupling strengths, leading to distinctive and asymmetrical spectral signature lines. The results of the study provide insights into quantifying dot-to-dot electronic coupling through photoelectron spectra, taking into account factors such as inter-dot separation distance, dot size, semiconductor type, and energy alignment of single-particle states.