Surface Control of Doping in Self-Doped Nanocrystals

Adrien Robin (1) , Clément Livache (1, 2) , Sandrine Ithurria (1) , Emmanuelle Lacaze (3) , Benoit Dubertret (1) , Emmanuel Lhuillier (2, 3)

1 LPEM - Laboratoire de Physique et d'Etude des Matériaux (UMR 8213)
2 INSP-E6 - Physico-chimie et dynamique des surfaces
3 INSP-E6 - Physico-chimie et dynamique des surfaces

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.

Mots clés: HgSe; self-doping; Colloidal quantum dot; electrolyte gating; photoresponse; infrared

Domaines: Matériaux; Matière Condensée [cond-mat]

Adrien Robin, Clément Livache, Sandrine Ithurria, Emmanuelle Lacaze, Benoit Dubertret, et al.. Surface Control of Doping in Self-Doped Nanocrystals. ACS Applied Materials & Interfaces, 2016, 8 (40), pp.27122 - 27128. ⟨10.1021/acsami.6b09530⟩. ⟨hal-01438644⟩