Cobalt-doped ZnO nanocrystals: quantum confinement and surface effects from ab initio methods

Schoenhalz, Aline L.; Dalpian, Gustavo M.

doi:10.1039/c3cp51395e

Cited by 13 publications

(13 citation statements)

References 44 publications

(50 reference statements)

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“…It is well known that in semiconductor nanocrystals, when the nanoparticle dimension becomes comparable to the bulk excitonic Bohr radius, the bandgap of the nanomaterial tends to increase due to the quantum confinement effect [236][237][238]. By proper tuning of the particle size, one can effectively enhance the bandgap, and especially for TSO nanomaterials, this bandgap enhancement is very useful for photovoltaics and other TSO electronics [239][240][241][242][243][244][245].…”

Section: Electro-optical Propertiesmentioning

confidence: 99%

Recent developments in TiO2 as n- and p-type transparent semiconductors: synthesis, modification, properties, and energy-related applications

2015

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TiO 2 -based thin films and nanomaterials have been fabricated via physical and solution-based techniques by various research groups around the globe. Generally, most applications of TiO 2 involve photocatalytic activity for water and air purification, self-cleaning surfaces, antibacterial activity, and superhydrophilicity. As a widebandgap semiconductor, modified TiO 2 belongs to a class of materials called transparent semiconducting oxides (TSOs), which are simultaneously optically transparent and electrically conductive. TSOs continue to be in high demand for a variety of applications ranging from transparent electronics and sensor devices to light detecting and emitting devices in telecommunications. However, reports on TiO 2 applications as an effective TSO for transparent electronics applications have been limited. In general, TiO 2 is intrinsically an n-type semiconductor but can be doped to have p-type semiconductivity. This provides a very important opportunity to fabricate all-transparent homojunction devices for light harvesting and energy storage. P-type TSOs have recently attracted tremendous interest in the field of active devices for emerging transparent electronics for potential use in ultra-violet light-based solar cells. Therefore, a detailed overview of the synthesis, band structure modification via doping, properties, and applications of modified TiO 2 as n-and p-type TSOs is warranted. This article comprehensively reviews the latest developments. The discussion includes solution-based wet chemical techniques and vacuum-based dry physical techniques fabricating TiO 2 -TSOs. The synthesis of p-TiO 2 in particular is discussed in detail as it may provide interesting breakthroughs in emerging transparent electronics applications. Also, the structural, optical, and electrical properties of TiO 2 are discussed in the context of TSO applications, specifically the defect chemistry of TiO 2 to obtain n-and p-type semiconductivity, which could provide interesting insights into the band structure engineering of TiO 2 for conductivity reversal. Applications of both nand p-type TiO 2 have been reviewed in detail in relation to thin film transparent homo/heterojunction devices, dyesensitized solar cells, electrochromic displays, and other energy-related applications.

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Section: Electro-optical Propertiesmentioning

confidence: 99%

Recent developments in TiO2 as n- and p-type transparent semiconductors: synthesis, modification, properties, and energy-related applications

2015

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“…These results are in reasonable agreement with the results on Co doped ZnO nanocrystals where it has been discussed the strong localization these levels. [9]…”

Section: Resultsmentioning

confidence: 99%

“…In order to modify or introduce new functionalities, several strategies have been adopted, such as the incorporation of impurity atoms. In particular, cobalt doped ZnO nanostructures have been largely investigated in the past years both experimentally and theoretically . The importance of Co in ZnO doping involves the production of red luminescence and under certain preparation conditions the appearance of ferromagnetic properties …”

Section: Introductionmentioning

confidence: 99%

Exploring Surface Effects in Co Doped ZnO Nanowires With Hybrid‐Density Functional Theory

Rosa

Tacca

Frauenheim

2018

Physica Status Solidi (b)

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In this work, density‐functional theory with hybrid functionals is employed to investigate the atomic and electronic structure of bare and hydrogenated Co doped ZnO nanowires. It is found that, in the absence of passivation on the nanowire surface, the cobalt atoms segregate to the surface. On the other hand, under hydrogen passivation, the incorporation of Co is more favorable at inner sites. This suggests that the incorporation of Co in nanostructures has a dependence on the environment and may be facilitated by adsorption of external atoms and relaxation of the wire surface.

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“…A prototype case for studying this system is Co-doped ZnO nanocrystals (Schoenhalz and Dalpian 2013). There are plenty of theoretical and experimental results for the bulk system, with strong controversies about its ground state.…”

Section: Interaction Between Surfaces and Magnetic Impuritiesmentioning

confidence: 99%

Spins in Semiconductor Nanocrystals

Dalpian¹

2018

Handbook of Materials Modeling

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Semiconductor nanocrystals are being used as hosts to trap and manipulate single spins. Spins in nanocrystals can have different properties than their bulk counterparts, owing both to quantum confinement and surface effects. We will show that spins can be generated in nanocrystals by the insertion of impurities, either magnetic or not, or by magnetic polarons present at dangling bonds at their surfaces.This chapter reports theoretical contributions to this field, where the Density Functional Theory is used to simulate these functionalized nanocrystals.

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Cobalt-doped ZnO nanocrystals: quantum confinement and surface effects from ab initio methods

Cited by 13 publications

References 44 publications

Recent developments in TiO2 as n- and p-type transparent semiconductors: synthesis, modification, properties, and energy-related applications

Recent developments in TiO2 as n- and p-type transparent semiconductors: synthesis, modification, properties, and energy-related applications

Exploring Surface Effects in Co Doped ZnO Nanowires With Hybrid‐Density Functional Theory

Spins in Semiconductor Nanocrystals

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