title: Surface Control of Doping in Self-Doped Nanocrystals.
abstract: Self-doped nanocrystals raise great interest for infrared (IR) optoelectronics because their optical properties span from near to far IR. However, their integration for photodetection requires a fine understanding of the origin of their doping and also a way to control the magnitude of the doping. In this paper, we demonstrate that a fine control of the doping level between 0.1 and 2 electrons per dot is obtained through ligand exchange. The latter affects not only the interparticle coupling but also their optical properties because of the band-shift resulting from the presence of surface dipoles. We demonstrate that self-doping is a bulk process and that surface dipoles can control its magnitude. We additionally propose a model to quantify the dipole involved with each ligand. We eventually use the ligand design rule previously evidenced to build a near-infrared photodetector on a soft and transparent substrate. The latter significantly improves the performance compared to previously reported colloidal quantum dot-based photodetectors on plastic substrates operated in the telecom wavelength range.
authors.affiliation: Laboratoire de Physique et d'Etude des Matériaux, ESPCI-ParisTech, PSL Research University, Sorbonne Université UPMC Univ Paris 06, CNRS , 10 rue Vauquelin, 75005 Paris, France.|Nexdot, Biocitech , 102 avenue Gaston Roussel, 93230 Romainville, France.
authors.forename: Adrien
authors.initials: A
authors.lastname: Robin
authors.affiliation: Laboratoire de Physique et d'Etude des Matériaux, ESPCI-ParisTech, PSL Research University, Sorbonne Université UPMC Univ Paris 06, CNRS , 10 rue Vauquelin, 75005 Paris, France.|Sorbonne Universités, UPMC Univ Paris 06, CNRS-UMR 7588 , Institut des NanoSciences de Paris, 4 place jussieu, 75005 Paris, France.
authors.forename: Clément
authors.initials: C
authors.lastname: Livache
authors.affiliation: Laboratoire de Physique et d'Etude des Matériaux, ESPCI-ParisTech, PSL Research University, Sorbonne Université UPMC Univ Paris 06, CNRS , 10 rue Vauquelin, 75005 Paris, France.
authors.forename: Sandrine
authors.initials: S
authors.lastname: Ithurria
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, CNRS-UMR 7588 , Institut des NanoSciences de Paris, 4 place jussieu, 75005 Paris, France.
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Lacaze
authors.affiliation: Laboratoire de Physique et d'Etude des Matériaux, ESPCI-ParisTech, PSL Research University, Sorbonne Université UPMC Univ Paris 06, CNRS , 10 rue Vauquelin, 75005 Paris, France.
authors.forename: Benoit
authors.initials: B
authors.lastname: Dubertret
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, CNRS-UMR 7588 , Institut des NanoSciences de Paris, 4 place jussieu, 75005 Paris, France.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Lhuillier
keywords: HgSe; colloidal quantum dot; electrolyte gating; infrared; photoresponse; self-doping