Cation/Anion Exchange Reactions toward the Syntheses of Upgraded Nanostructures: Principles and Applications

Abstract

The last 5 years have witnessed rapid progress in the field of hybrid nanostructures toward enhanced optical and electronic properties. On this topic, we focus on the relevant progress that has been achieved on the basis of cation/anion exchange reactions (CERs/AERs). Different from those direct synthesis strategies, CERs/AERs can offer more freedom in tuning the chemical composition, crystal phases, doping, interfaces, and morphologies, which are key parameters to determine the optical and electronic properties of the target products. We present several examples, e.g., doped quantum dots (QDs), engineered core-shell QDs, metal-semiconductor hybrid nanostructures, hollow structures, and inorganic perovskite nanocrystals. These upgraded structures afforded by CERs/ AERs generally exhibit improved properties, such as increased quantum yields, prolonged lifetimes, and well-engineered band gaps for charge transportation and recombination, thus providing more opportunities for further advanced applications.

Carrier Dynamics in Alloyed Chalcogenide Quantum Dots and Their Light‐Emitting Devices

“…The confinement potential of alloyed QDs could be tuned by their sizes and component stoichiometries. Due to their superior optoelectronic properties, multicomponent alloyed QDs, such as CdSeS, ZnCdSe, ZnTeSe, ZnCdSeS, [70][71][72][73][74][75][76] were developed by researchers.…”

Pb‐Doped Ag2Se Quantum Dots with Enhanced Photoluminescence in the NIR‐II Window

“…[ 24 ] Nonetheless, we find that postsynthetic modification of cation exchange (CE) is an advantageous tool since CE reactions are very often topotactic. [ 25–27 ] During CE, the anionic sublattice is conserved and the cations are exchanged, preserving the crystal structure of the goal QDs as the parent QDs. In addition, the doping level regulation of CE was easily controlled by the doping precursor concentration, and further the undoped QDs could be directly compared with the subsequently doped QDs.…”

Metal Cation Valency Dependence in Morphology Evolution of Cu2−xS Nanodisk Seeds and Their Pseudomorphic Cation Exchanges

“…In general, native metal ions in parent NPs are fully or partially substituted by foreign cations, whereas the anion sublattice remains virtually intact. In most cases, the products inherit the morphology and crystal phase of the parent NP [16–19] . Among the CE templates, there has been growing attention on nonstoichiometric copper chalcogenide Cu 2− x E (E=S, Se, and Te) NPs mainly owing to their high copper ion mobility in NP lattice, variable copper vacancies as well as diverse crystal phases and morphologies, which dramatically affect the CE reaction kinetics and thermodynamics, and therefore, the production of complex nanostructures and phases [20–32] .…”

“…In most cases, the products inherit the morphologya nd crystal phase of the parent NP. [16][17][18][19] Amongt he CE templates, there has been growing attention on nonstoichiometric copper chalcogenide Cu 2Àx E( E = S, Se, and Te )N Ps mainly owing to their high copperi on mobilityi n NP lattice, variable copperv acancies as well as diverse crystal phases and morphologies, which dramatically affect the CE reaction kinetics and thermodynamics, and therefore, the productiono fc omplex nanostructures and phases. [20][21][22][23][24][25][26][27][28][29][30][31][32] Furthermore, the catalytic and optical properties of the CE product, such as ZnE, CdE and their according heterostructures, strongly rely on the NP morphology.…”