Polyoxometalate as Control Agent for the Doping in HgSe Self-Doped Nanocrystals

Intraband and plasmonic transitions have appeared over the last years as an interesting tool to achieve optical absorption in the mid-infrared. Tuning the doping magnitude has become a major challenge not only to tune the optical spectrum but also properties such as the dark current or the time response. Here, we investigate the case of self-doped HgSe colloidal quantum dots (CQDs). At present, tuning of the doping relies on band bending induced by a dipole design at the nanoparticle surface. With such a surface gating approach, it is difficult to conciliate both massive tuning of the Fermi level and the preservation of transport properties of the CQD arrays. Here, we propose a strategy to graft functionalized polyoxometalates (POMs) at the CQD surface and obtain simultaneously a massive tuning of the carrier density (≈5 electrons per nanoparticle) and conduction properties. We bring a consistent demonstration of the HgSe CQD doping decrease by a charge transfer to the POM. This method is highly promising...