Tailoring Transition Dipole Moment in Colloidal Nanocrystal Thin Film on Nanocomposite Materials

Controlling the transition dipole moment is extremely important for various photophysical characteristics in semiconductors. Especially, suppression of Auger recombination in quantum dots (QDs) is essential for the development of novel applications, including bioimaging, lasing, and optoelectronic devices. To date, most of the studies on the Auger process are conducted on the basis of manipulating the material property such as wavefunction of electron and hole, energy band, and confinement potential. However, a new way of tuning the Auger process using nanocomposite materials is not reported. In this work, the biexciton Auger recombination (BAR) process in CdSe/CdS(1 ML) nanocrystal thin-film is successfully controlled by introducing nanocomposite materials. Performing pump intensity-dependent transient absorption experiments, a significant reduction (up to 30%) of BAR rate is observed in the presence of nanocomposite structures. This notable suppression effect is attributed to the modulation of the net transition dipole moment. These findings will provide further insight into the rational design of QDs combining with a nanostructure that efficiently suppresses Auger recombination rates.