Wed, Jan. 6, 2016, 3:15pm
Frick Chemistry Laboratory, Taylor Auditorium
Host: Gregory Scholes
Electronically doped colloidal semiconductor nanocrystals
The introduction of excess, delocalized charge carriers into semiconductors is a vital component to the advancement of many technologies. This electronic doping, however, remains a longstanding experimental challenge, particularly in colloidal semiconductor nanocrystals where surface chemistries often contribute to charge-trapping. Unlike many strategies, the process of photodoping allows post-synthetic, tunable and reversible addition of excess charge carriers that may be quantified via chemical titration. We investigate the factors limiting photochemical reduction of colloidal semiconductor nanocrystals and show that accumulation of excess conduction band electrons is dependent on the size and identity of the host nanocrystal as well as the sacrificial reductant. The flexibility of photodoping has enabled several photophysical investigations on n-doped colloidal nanocrystals, including identification of quantum-confined plasmons and quantification of negative trion Auger size dependence. The results of these photophysical measurements will be discussed.