Multifunctional Sn- and Fe-Codoped In₂O₃Colloidal Nanocrystals: Plasmonics and Magnetism

Abstract

We prepared Fe- and Sn-codoped colloidal In2O3 nanocrystals (∼6 nm). Sn doping provides free electrons in the conduction band, originating localized surface plasmon resonance (LSPR) and electrical conductivity. The LSPR band can be tuned between 2000 and >3000 nm, depending on the extent and kind of dopant ions. Fe doping, on the other hand, provides unpaired electrons, resulting in weak ferromagnetism at room temperature. Fe doping shifts the LSPR band of 10% Sn-doped In2O3 nanocrystals to a longer wavelength along with a reduction in intensity, suggesting trapping of charge carriers around the dopant centers, whereas Sn doping increases the magnetization of 10% Fe-doped In2O3 nanocrystals, probably because of the free electron mediated interactions between distant magnetic ions. The combination of plasmonics and magnetism, in addition to electronic conductivity and visible-light transparency, is a unique feature of our colloidal codoped nanocrystals.

A straightforward and “green” solvothermal synthesis of Al doped zinc oxide plasmonic nanocrystals and piezoresistive elastomer nanocomposite

“…Plasmonic semiconductor oxide nanocrystals such as Al-doped ZnO (AZO), [1][2][3] indium-doped ZnO (IZO), 3,4 Ga-doped ZnO (GZO), 3 Sn-doped In 2 O 3 (ITO), [6][7] Sb-doped SnO 2 (ATO) 8,9 or others [10][11][12][13][14] have attracted growing attention due to their applicability in many optoelectronic applications, such as nearinfrared selective electrochromic devices, 15 (flexible) displays 11 and polymer light emitting diodes. 4 They also demonstrate excellent bio-sensing and chemical sensing capabilities 16 .…”

Doping Controls Plasmonics, Electrical Conductivity, and Carrier-Mediated Magnetic Coupling in Fe and Sn Codoped In2O3Nanocrystals: Local Structure Is the Key

“…1 Also, no impurity peak was observed in XRD data of Fe−Sn codoped In 2 O 3 NCs. 1 Another possible reason for reduction of free electron concentration with Fe doping could be that the Sn concentration remains the same producing an equal number of free electrons both in the presence and absence of Fe, but Fe 3+ takes up some of those free electrons converting to Fe 2+ . In fact, prior studies on Fe-doped In 2 O 3 bulk samples have indicated when the sample is treated under reducing conditions, Fe 3+ can get reduced by consuming the electron obtained from oxygen vacancies as suggested by eq 1.…”

“…1 Sn doping provides free electrons for LSPR and Fe doping provides magnetic spin. In this paper, we control the interaction between two kinds of dopants in Fe−Sn codoped In 2 O 3 nanocrystals, via probing the atomic bonding and ion valence of dopant ions.…”

Luminescence, Plasmonic, and Magnetic Properties of Doped Semiconductor Nanocrystals

“…[49] Thed ensity of these valence band holes can be reversibly controlled by employing areducing or an oxidizing atmosphere,t hereby allowing reversible tuning of the LSPR band. [11,[52][53][54][55] Similar to bulk TCOs in which oxygen vacancies promote ntype doping,t he LSPR from TCO nanocrystals is also dominated by n-type doping.Atypical LSPR band from Sn 4+ -doped In 2 O 3 (ITO) nanocrystals is shown in Figure 6c. [12,51] On the other hand, bulk and thin films of transparent conducting oxides (TCO) exhibit ahigh density of delocalized electrons in the conduction band.…”