title: Highly effective surface passivation of PbSe quantum dots through reaction with molecular chlorine.
abstract: PbSe nanocrystal quantum dots (NQDs) are a promising active material for a range of optoelectronic devices, including solar cells, high-sensitivity infrared (IR) photodetectors, and IR-emitting diodes and lasers. However, device realization has been constrained by these NQDs' chemical instability toward oxidation, which leads to uncontrollable changes in optical and electronic properties. Here, we present a simple method to enhance the stability of PbSe NQDs against oxidation and to improve their optical properties through reaction with molecular chlorine. The chlorine molecules preferentially etch out surface Se ions and react with Pb ions to form a thin (1-2 monolayers) PbCl(x) passivation layer which effectively prevents oxidation during long-term air exposure while passivating surface trap states to increase photoluminescence efficiency and decrease photocharging. Our method is simple, widely applicable to PbSe and PbS NQDs of a range of sizes, compatible with solution-based processes for fabricating NQD-based devices, and effective both in solution and in solid NQD films; thus, it is a practical protocol for facilitating advances over the full range of optoelectronic applications.
authors.affiliation: Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States.
authors.forename: Wan Ki
authors.initials: WK
authors.lastname: Bae
authors.forename: Jin
authors.initials: J
authors.lastname: Joo
authors.forename: Lazaro A
authors.initials: LA
authors.lastname: Padilha
authors.forename: Jonghan
authors.initials: J
authors.lastname: Won
authors.forename: Doh C
authors.initials: DC
authors.lastname: Lee
authors.forename: Qianglu
authors.initials: Q
authors.lastname: Lin
authors.forename: Weon-kyu
authors.initials: WK
authors.lastname: Koh
authors.forename: Hongmei
authors.initials: H
authors.lastname: Luo
authors.forename: Victor I
authors.initials: VI
authors.lastname: Klimov
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Pietryga
mesh_terms: D002713:Chlorine / Q000737:chemistry*; D007854:Lead / Q000737:chemistry*; D045663:Quantum Dots; D018036:Selenium Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D018036:Selenium Compounds; C088065:lead selenide; D007854:Lead; D002713:Chlorine