title: Ultrastable PbSe nanocrystal quantum dots via in situ formation of atomically thin halide adlayers on PbSe(100).
abstract: The fast degradation of lead selenide (PbSe) nanocrystal quantum dots (NQDs) in ambient conditions impedes widespread deployment of the highly excitonic, thus versatile, colloidal NQDs. Here we report a simple in situ post-synthetic halide salt treatment that results in size-independent air stability of PbSe NQDs without significantly altering their optoelectronic characteristics. From TEM, NMR, and XPS results and DFT calculations, we propose that the unprecedented size-independent air stability of the PbSe NQDs can be attributed to the successful passivation of under-coordinated PbSe(100) facets with atomically thin PbX2 (X = Cl, Br, I) adlayers. Conductive films made of halide-treated ultrastable PbSe NQDs exhibit markedly improved air stability and behave as an n-type channel in a field-effect transistor. Our simple in situ wet-chemical passivation scheme will enable broader utilization of PbSe NQDs in ambient conditions in many optoelectronic applications.
authors.affiliation: Nanomechanical Systems Research Division, Korea Institute of Machinery and Materials (KIMM) , Daejeon 305-343, Korea.
authors.forename: Ju Young
authors.initials: JY
authors.lastname: Woo
authors.forename: Jae-Hyeon
authors.initials: JH
authors.lastname: Ko
authors.forename: Jung Hoon
authors.initials: JH
authors.lastname: Song
authors.forename: Kyungnam
authors.initials: K
authors.lastname: Kim
authors.forename: Hyekyoung
authors.initials: H
authors.lastname: Choi
authors.forename: Yong-Hyun
authors.initials: YH
authors.lastname: Kim
authors.forename: Doh C
authors.initials: DC
authors.lastname: Lee
authors.forename: Sohee
authors.initials: S
authors.lastname: Jeong