n-Type PbSe Quantum Dots via Post-Synthetic Indium Doping.

Journal of the American Chemical Society (2018-09-27)
Haipeng Lu, Gerard M Carroll, Xihan Chen, Dinesh K Amarasinghe, Nathan R Neale, Elisa M Miller, Peter C Sercel, Federico A Rabuffetti, Alexander L Efros, Matthew C Beard
ABSTRACT

We developed a postsynthetic treatment to produce impurity n-type doped PbSe QDs with In3+ as the substitutional dopant. Increasing the incorporated In content is accompanied by a gradual bleaching of the interband first-exciton transition and concurrently the appearance of a size-dependent, intraband absorption, suggesting the controlled introduction of delocalized electrons into the QD band edge states under equilibrium conditions. We compare the optical properties of our In-doped PbSe QDs to cobaltocene treated QDs, where the n-type dopant arises from remote reduction of the PbSe QDs and observe similar behavior. Spectroelectrochemical measurements also demonstrate characteristic n-type signatures, including both an induced absorption within the electrochemical bandgap and a shift of the Fermi-level toward the conduction band. Finally, we demonstrate that the In3+ dopants can be reversibly removed from the PbSe QDs, whereupon the first exciton bleach is recovered. Our results demonstrate that PbSe QDs can be controllably n-type doped via impurity aliovalent substitutional doping.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Oleic acid, technical grade, 90%
Sigma-Aldrich
Ferrocene, 98%
Sigma-Aldrich
Octane, anhydrous, ≥99%
Sigma-Aldrich
Diphenylphosphine, 98%
Sigma-Aldrich
Tetrachloroethylene, anhydrous, ≥99%
Sigma-Aldrich
Bis(cyclopentadienyl)cobalt(II)