title: Photochemical electronic doping of colloidal CdSe nanocrystals.
abstract: A method for electronic doping of colloidal CdSe nanocrystals (NCs) is reported. Anaerobic photoexcitation of CdSe NCs in the presence of a borohydride hole quencher, Li[Et3BH], yields colloidal n-type CdSe NCs possessing extra conduction-band electrons compensated by cations deposited by the hydride hole quencher. The photodoped NCs possess excellent optical quality and display the key spectroscopic signatures associated with NC n-doping, including a bleach at the absorption edge, appearance of a new IR absorption band, and Auger quenching of the excitonic photoluminescence. Although stable under anaerobic conditions, these spectroscopic changes are all reversed completely upon exposure of the n-doped NCs to air. Chemical titration of the added electrons confirms previous correlations between absorption bleach and electron accumulation and provides a means of quantifying the extent of electron trapping in some NCs. The generality of this photodoping method is demonstrated by initial results on colloidal CdE (E = S, Te) NCs as well as on CdSe quantum dot films.
authors.affiliation: Department of Chemistry, University of Washington , Seattle, Washington 98195-1700, United States.
authors.forename: Jeffrey D
authors.initials: JD
authors.lastname: Rinehart
authors.forename: Alina M
authors.initials: AM
authors.lastname: Schimpf
authors.forename: Amanda L
authors.initials: AL
authors.lastname: Weaver
authors.forename: Alicia W
authors.initials: AW
authors.lastname: Cohn
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Gamelin