scholarly journals Molecular and Structural Probes of Defect States in Quantum Dots for Solar Photoconversion

2019 ◽  
Author(s):  
John Asbury ◽  
Keyword(s):  
Quantum Dots ◽  
Defect States ◽  
Structural Probes

scholarly journals Synthesis of luminescent core/shell α-Zn3P2/ZnS quantum dots

Nanoscale ◽  
2020 ◽  
Vol 12 (40) ◽  
pp. 20952-20964
Author(s):  
Ingrid J. Paredes ◽  
Clara Beck ◽  
Scott Lee ◽  
Shuzhen Chen ◽  
Mersal Khwaja ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Quantum Yield ◽  
Surface Oxidation ◽  
Core Shell ◽  
Defect States ◽  
Optoelectronic Applications

Optoelectronic applications of Zn3P2 quantum dots have long been hindered by surface oxidation and defect states leading to low PL quantum yield. The authors present shelling of Zn3P2 with ZnS to prevent oxidation and obtain luminescent particles.

Surface defect states of CdTexS1−x quantum dots

2009 ◽  
Vol 373 (48) ◽  
pp. 4475-4478 ◽  
Author(s):  
Jiaxiang Zhang ◽  
Xiaoyong Hu ◽  
Qihuang Gong
Keyword(s):  
Quantum Dots ◽  
Surface Defect ◽  
Defect States

scholarly journals Silicon Quantum Dots in a Dielectric Matrix for All-Silicon Tandem Solar Cells

2007 ◽  
Vol 2007 ◽  
pp. 1-11 ◽  
Author(s):  
Eun-Chel Cho ◽  
Martin A. Green ◽  
Gavin Conibeer ◽  
Dengyuan Song ◽  
Young-Hyun Cho ◽  
...  
Keyword(s):  
Thin Film ◽  
Quantum Dots ◽  
Quantum Confinement ◽  
Collection Efficiency ◽  
Film Material ◽  
Defect States ◽  
Silicon Quantum Dots ◽  
Rich Material ◽  
Silicon Based ◽  
Si Quantum Dots

We report work progress on the growth of Si quantum dots in different matrices for future photovoltaic applications. The work reported here seeks to engineer a wide-bandgap silicon-based thin-film material by using quantum confinement in silicon quantum dots and to utilize this in complete thin-film silicon-based tandem cell, without the constraints of lattice matching, but which nonetheless gives an enhanced efficiency through the increased spectral collection efficiency. Coherent-sized quantum dots, dispersed in a matrix of silicon carbide, nitride, or oxide, were fabricated by precipitation of Si-rich material deposited by reactive sputtering or PECVD. Bandgap opening of Si QDs in nitride is more blue-shifted than that of Si QD in oxide, while clear evidence of quantum confinement in Si quantum dots in carbide was hard to obtain, probably due to many surface and defect states. The PL decay shows that the lifetimes vary from 10 to 70 microseconds for diameter of 3.4 nm dot with increasing detection wavelength.

scholarly journals Metallic phase transition metal dichalcogenide quantum dots showing different optical charge excitation and decay pathways

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Bo-Hyun Kim ◽  
Min-Ho Jang ◽  
Hyewon Yoon ◽  
Hyun Jun Kim ◽  
Yong-Hoon Cho ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Transition Metal ◽  
Photophysical Properties ◽  
Quantum Confinement Effect ◽  
Stokes Shift ◽  
Transition Metal Dichalcogenides ◽  
Metallic Phase ◽  
Excitation Wavelength ◽  
Transition Metal Dichalcogenide ◽  
Defect States

AbstractThe charge excitation and decay pathways of two-dimensional heteroatomic quantum dots (QDs) are affected by the quantum confinement effect, bandgap structure and strong exciton binding energy. Recently, semiconducting transition metal dichalcogenides (TMDs) have been intensively studied; however, the charge dynamics of metallic phase QDs (mQDs) of TMDs remain relatively unknown. Herein, we investigate the photophysical properties of TMD-mQDs of two sizes, where the TMD-mQDs show different charge excitation and decay pathways that are mainly ascribed to the defect states and valence band splitting, resulting in a large Stokes shift and two excitation bands for maximum photoluminescence (PL). Interestingly, the dominant excitation band redshifts as the size increases, and the time-resolved PL peak redshifts at an excitation wavelength of 266 nm in the smaller QDs. Additionally, the lifetime is shortened in the larger QDs. From the structural and theoretical analysis, we discuss that the charge decay pathway in the smaller QDs is predominantly affected by edge oxidation, whereas the vacancies play an important role in the larger QDs.

SURFACE LUMINESCENCE OF A2B6 SEMICONDUCTOR QUANTUM DOTS (REVIEW)

2021 ◽  
Vol 56 ◽  
pp. 27-38
Author(s):  
D. V. Korbutyak ◽  
Keyword(s):  
Quantum Dots ◽  
Surface Defect ◽  
Chemical Nature ◽  
Lattice Relaxation ◽  
Localized States ◽  
Exciton Luminescence ◽  
Defect States ◽  
Semiconductor Compounds ◽  
Surface Luminescence ◽  
Ab Initio Approach

Semiconductor zero-dimensional nanocrystals – quantum dots (QDs) – have been increasingly used in various fields of opto- and nanoelectronics in recent decades. This is because of the exciton nature of their luminescence, which can be controlled via the well known quantum-dimensional effect. At the same time, at small nanocrystall sizes, the influence of the surface on the optical and structural properties of nanocrystals increases significantly. The presence of broken bonds of surface atoms and point defects – vacancies and interstial atoms – can both weaken the exciton luminescence and create new effective channels of radiant luminescence. In some cases, these surface luminescence becomes dominant, leading to optical spectra broadening up to the quasi-white light. The nature of such localized states often remains unestablished due to the large number of the possible sorts of defects in both of QD and its surrounding. In contrast to exciton luminescence, which can be properly described within effective-mass approximations, the optical properties of defects relay on chemical nature of both defect itsself and its surrounding, what cannot be provided by “hydrogen-type coulomb defect” approximation. Moreover, charge state and related to this lattice relaxation must be taken into account, what requires an application of atomistic approach, such as Density functioal theory (DFT). Therefore, this review is devoted to the study of surface (defect) states and related luminescence, as well as the analysis of possible defects in nanocrystals of semiconductor compounds A2B6 (CdS, CdZnS, ZnS), responsible for luminescence processes, within ab initio approach. The review presents the results of the authors' and literature sources devoted to the study of the luminescent characteristics of ultra-small (<2 nm) QDs.

Defect states in hybrid solar cells consisting of Sb2S3 quantum dots and TiO2 nanoparticles

2013 ◽  
Vol 103 (2) ◽  
pp. 023901 ◽  
Author(s):  
Dong Uk Lee ◽  
Sang Woo Pak ◽  
Seong Gook Cho ◽  
Eun Kyu Kim ◽  
Sang Il Seok
Keyword(s):  
Quantum Dots ◽  
Solar Cells ◽  
Tio2 Nanoparticles ◽  
Hybrid Solar Cells ◽  
Defect States
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