Interface Engineering of Mn-Doped ZnSe-Based Core/Shell Nanowires for Tunable Host–Dopant Coupling

Abstract

Transition metal ion doped one-dimensional (1-D) nanocrystals (NCs) have advantages of larger absorption cross sections and polarized absorption and emissions in comparison to 0-D NCs. However, direct synthesis of doped 1-D nanorods (NRs) or nanowires (NWs) has proven challenging. In this study, we report the synthesis of 1-D Mn-doped ZnSe NWs using a colloidal hot-injection method and shell passivation for core/shell NWs with tunable optical properties. Experimental results show optical properties of the NWs are controlled by the composition and thickness of the shell lattice. It was found that both the host-Mn energy transfer and Mn-Mn coupling are strongly dependent on the type of alloy at the interface of doped core/shell NWs. For Mn-doped type I ZnSe/ZnS core/shell NWs, the ZnS shell passivation can enhance florescence quantum yield with little effect on the location of the incorporated Mn dopant due to the identical cationic Zn site available for Mn dopants throughout the core/shell NWs. However, for Mn-doped quasi type II ZnSe/CdS NWs and ZnSe/CdS/ZnS core/shell NWs, the cation alloying (ZnCdS(e)) can lead to metal dopant migration from the core to the alloyed interface and tunable host-dopant energy transfer efficiencies and Mn-Mn coupling. As a result, a tunable dual-band emission can be achieved for the doped NWs with the cation-alloyed interface. The interfacial alloying mediated energy transfer and Mn-Mn coupling provides a method to control the optical properties of the doped 1-D core/shell NWs.

Electron Transfer Going the Distance: Mn-Doped ZnSe as a Model Photocatalytic System

“…For example, an excitonic excited state of a host ZnSe nanocrystal can transfer energy to a Mn ion via an Auger-like spin-exchange process that depends on the coupling of the Mn 3d 5 electrons with the nanocrystal conduction and valence band electrons. − Importantly, the electronic transition between the excited 4 T 1 state of the Mn ions and the 6 A 1 ground state involves a spin change, which makes electronic relaxation of the excited 4 T 1 state a spin-forbidden process. This is the origin of the uniquely long excited state lifetime of such Mn-doped nanocrystals, which can extend into the millisecond time regime. ,− …”

Gd-doped CuBi2O4/CuO heterojunction film photocathodes for photoelectrochemical H2O2 production through oxygen reduction

“…Possibly, too small doping concentration of Gd 3+ ions could not produce significant surface electronic effect. However, excessive doping of Gd 3+ ions could form recombination center of photogenerated carriers due to the dopant concentration quenching effect [41]. In addition, H2O2 yield is pH-dependent (Fig.…”

Recent Advances in Zinc‐Containing Colloidal Semiconductor Nanocrystals for Optoelectronic and Energy Conversion Applications

“…Those doped nanostructures exhibit enhanced fluorescence and controlled electronic and magnetic properties . Compared with Mn doped type‐I ZnSe/ZnS core shell nanowires (Figure a,c), Mn doped quasi type II/type I ZnSe/CdS/ZnS double shell nanowires showed shell thickness‐dependent emission wavelength and quantum yields (Figure b,d) . By increasing the shell thickness, the emission of Mn doped ZnSe/ZnS core shell nanowires shifted from 540 to 640 nm, while the emission center of Mn doped ZnSe/CdS/ZnS double shell nanowires transferred from Mn center of 590 nm to ZnSe/CdS heterostructure of 475 nm.…”