Harvesting a Wide Spectral Range of Electronic Coherences with Disordered Quasi-Homo Dimeric Assemblies at Room Temperature

A wide variety of photoinduced electronic coherences are shown to be robust with respect to dephasing in ensembles of quasi-homodimers assembled with sub-nm ligands from colloidal 3 nm CdSe quantum dots (QDs) with controlled 9% size dispersion, both in solution and in solid-state. Coherence periods ranging from 40 to 300 fs are consistently characterized by multidimensional electronic spectroscopy in the Vis range in solution and solid-state samples. A theoretical model that includes size dispersion, spin orbit coupling, and crystal field splitting supports the assignment of electronic coherences. Further, this model provides a guide for optimizing the coherences by tuning the interplay between dimer electronic delocalization, optical activity, and size dispersion. The experimental persistence of many QD electronic coherences at the level of the size dispersed ensemble in the solid-state and in solution opens the way for building versatile bottom-up materials well suited to quantum technology applications.