2D Colloidal Metal Chalcogenides Semiconductors: Synthesis, Spectroscopy, and Applications

Emmanuel Lhuillier (1, 1) , Silvia Pedetti (1) , Sandrine Ithurria (1) , Brice Nadal (2) , Hadrien Heuclin (2) , Benoit Dubertret (1)

1 LPEM - Laboratoire de Physique et d'Etude des Matériaux (UMR 8213)
2 Nexdot

Semiconductors are at the basis of electronics. Up to now, most devices that contain semiconductors use materials obtained from a top down approach with semiconductors grown by molecular beam epitaxy or chemical vapor deposition. Colloidal semiconductors nanoparticles have been synthesized for more than 30 years now, and their synthesis is becoming mature enough so that these nanoparticles start to be incorporated into devices. An important development that recently took place in the field of colloidal quantum dots is the synthesis of 2 dimensional semiconductor nanoplatelets that appear as free standing nanosheets. These 2D colloidal systems are the newborn in the family of shaped-controlled nanoparticles that started with spheres, was extended with rods and wires, continued with tetrapods, and that now ends with platelets. From a physical point of view, these objects bring the 1D-confined particles into the colloidal family. It is a notable addition, since these platelets can have a thickness that is controlled with atomic precision, so that no inhomogeneous broadening is observed. Because they have two large free interfaces, the mirror charges play an important role, and the binding energy of the exciton is extremely large. These two effects almost perfectly compensate each other, but it results in particles with unique spectroscopic properties such as fast fluorescent lifetimes and extreme color purity (narrow full width at half maximum of their emission spectra). These nanoplatelets with extremely large confinement, but very simple and well defined chemistry, are model systems to check and further develop, notably with the incorporation in the models of the organic/inorganic interface, various theoretical approaches used for colloidal particles. From a chemical point of view, these colloidal particles are a model system to study the role of ligands since they have precisely defined surfaces. In addition, the synthesis of these highly anisotropic objects triggered new research to understand at a mechanistic level how this strong anisotropy could be generated. Luckily, some of the chemical know-how built with the spherical and rod-shaped particles is being transferred-with some adaptation-to the 2D systems, so that 2D core/shell and core/crown hetero-structures have recently been introduced. These objects are very interesting because they suggest that multiple quantum wells, that are at the basis of large-scale applications, could be grown in solution. From the application point of view, 2D colloidal nanoplatelets offer interesting perspectives when color purity, charge conductivity, or field tunable absorption are required. In this account, we review the chemical synthesis, the physical properties and the applications of colloidal semiconductor nanoplatelets with an emphasis on the zinc-blende nanoplatelets that were developed more specifically in our group.

Domaines: Matériaux

Emmanuel Lhuillier, Silvia Pedetti, Sandrine Ithurria, Brice Nadal, Hadrien Heuclin, et al.. 2D Colloidal Metal Chalcogenides Semiconductors: Synthesis, Spectroscopy, and Applications. Accounts of Chemical Research, 2015, 48 (1), pp.22 - 30. ⟨10.1021/ar500326c⟩. ⟨hal-01438557⟩