Interface control of electronic and optical properties in IV–VI and II–VI core/shell colloidal quantum dots: a review

Jang, Youngjin; Shapiro, Arthur; Isarov, Maya; Rubin-Brusilovski, Anna; Safran, Aron; Budniak, Adam K.; Horani, Faris; Dehnel, Joanna; Sashchiuk, Aldona; Lifshitz, Efrat

doi:10.1039/c6cc08742f

Cited by 97 publications

(89 citation statements)

References 294 publications

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“…Perovskite nanocrystals (PNCs) provide an exciting platform to investigate the extent of defect tolerance to higher energy states, owing to (i) their higher PLQY that facilitate the use of fluorescence techniques, (ii) the introduction of surfaces as inherently defective sites, and (iii) the possibility of controlling the passivation of these defects with effective surface chemistry tools [20][21][22] . In recent years, PNCs took the nanocrystals field by storm, outpacing traditional II-VI semiconductor NCs in many of their principal applications, e.g., lower MEG and ASE thresholds, longer-lived hot carriers and larger multiphoton cross-sections [23][24][25][26] .…”

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confidence: 99%

Hot carriers perspective on the nature of traps in perovskites

et al. 2020

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Amongst the many spectacular properties of hybrid lead halide perovskites, their defect tolerance is regarded as the key enabler for a spectrum of high-performance optoelectronic devices that propel perovskites to prominence. However, the plateauing efficiency enhancement of perovskite devices calls into question the extent of this defect tolerance in perovskite systems; an opportunity for perovskite nanocrystals to fill. Through optical spectroscopy and phenomenological modeling based on the Marcus theory of charge transfer, we uncover the detrimental effect of hot carriers trapping in methylammonium lead iodide and bromide nanocrystals. Higher excess energies induce faster carrier trapping rates, ascribed to interactions with shallow traps and ligands, turning these into potent defects. Passivating these traps with the introduction of phosphine oxide ligands can help mitigate hot carrier trapping. Importantly, our findings extend beyond photovoltaics and are relevant for low threshold lasers, light-emitting devices and multi-exciton generation devices.

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confidence: 99%

Hot carriers perspective on the nature of traps in perovskites

et al. 2020

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“…The stability of the colloidal QDs capped by organic ligands is limited due to week interaction between the surface atoms on QD surface and the organic ligands. Therefore, the design and epitaxial growth of shell over the core QD is an efficient approach to improve the surface passivation, which results in significantly reduces the surface traps/defects as well as improves both PL QY and long‐term stability toward surrounding environment 39,43,53,58,66–69. The choice of core/shell materials as well as the crystallization of shell layer in the same structure or small lattice mismatch with core structure, are most important parameters for the design and synthesis of core/shell QDs 39,40,43,70.…”

Section: Synthesis Of Colloidal Core/shell Qdsmentioning

confidence: 99%

Core/Shell Quantum Dots Solar Cells

Selopal

Zhao

Wang

et al. 2020

Adv Funct Materials

115

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Semiconductor nanocrystals, the so-called quantum dots (QDs), exhibit versatile optical and electrical properties. However, QDs possess high density of surface defects/traps due to the high surface-to-volume ratio, which act as nonradiative carrier recombination centers within the QDs, thereby deteriorating the overall solar cell performance. The surface passivation of QDs through the growth of an outer shell of different materials/compositions called "core/shell QDs" has proven to be an effective approach to reduce the surface defects and confinement potential, which can enable the broadening of the absorption spectrum, accelerate the carrier transfer, and reduce exciton recombination loss. Here, the recent research developments in the tailoring of the structure of core/shell QDs to tune exciton dynamics so as to improve solar cell performance are summarized. The role of band alignment of core and shell materials, core size, shell thickness/compositions, and interface engineering of core/thick shell called "giant" QDs on electron-hole spatial separation, carrier transport, and confinement potential, before and after grafting on the carrier scavengers (semiconductor/electrolyte), is described. Then, the solar cell performance based on core/shell QDs is introduced. Finally, an outlook for the rational design of core/shell QDs is provided, which can further promote the development of high-efficiency and stable QD sensitized solar cells.

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“…Till now, numerous epitaxial core@shell and core@multi-shell nanostructures made of group II-VI, IV-VI, and III-V semiconductors, such as CdSe@CdS [20,[47][48][49], CdS@ZnS [50][51][52][53], InP@ZnS [54][55][56][57], PbSe@PbS [58][59][60][61], PbSe@CdSe [62][63][64], ZnTe@CdSe [65][66][67], and CdSe@ZnTe-ZnS [68][69][70], have been prepared to enhance the PL, improve the stability, and tune the emission wavelength. The basic properties of different types of core@shell and core@multi-shell nanostructures with different chemical compositions and band alignment structures have been well summarized in several recent reviews [71][72][73]. Here, we only focus on the key factors that affect the construction of epitaxial configurations.…”

Section: Core@shell Nanostructuresmentioning

confidence: 99%

Wet-Chemical Synthesis and Applications of Semiconductor Nanomaterial-Based Epitaxial Heterostructures

Chen

et al. 2019

Nano-Micro Lett.

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HIGHLIGHTS• The synthesis of semiconductor nanomaterial-based epitaxial heterostructures by wet-chemical methods is introduced. Various architectures based on different kinds of seeds or templates are illustrated, and their growth mechanisms are discussed in detail.• The applications of epitaxial heterostructures in optoelectronics, thermoelectrics, and catalysis are discussed. ABSTRACTSemiconductor nanomaterial-based epitaxial heterostructures with precisely controlled compositions and morphologies are of great importance for various applications in optoelectronics, thermoelectrics, and catalysis. Until now, various kinds of epitaxial heterostructures have been constructed. In this minireview, we will first introduce the synthesis of semiconductor nanomaterial-based epitaxial heterostructures by wet-chemical methods. Various architectures based on different kinds of seeds or templates are illustrated, and their growth mechanisms are discussed in detail. Then, the applications of epitaxial heterostructures in optoelectronics, catalysis, and thermoelectrics are described. Finally, we provide some challenges and personal perspectives for the future research directions of semiconductor nanomaterial-based epitaxial heterostructures. C ata lys is L i g h te m it ti ng dev ic e P h o t o v ol taic de v ic e T h e r m al elect ic d e v i c e Semiconductor Epitaxial Heterostructuressolution containing Cd-oleate [33]. The thermal decomposition of (NH 4 ) 2 MoS 4 or (NH 4 ) 2 WS 4 not only provided the sulfur source for the nucleation and growth of CdS seeds, but also acted as the precursor which decomposed to form MoS 2 or WS 2 nanosheets (NSs). Hydro-/Solvothermal StrategyEpitaxial heterostructures can also be prepared by the hydro-/solvothermal strategy, a typical wet-chemical synthesis method, which uses water or organic solvents as the reaction medium in a sealed steel pressure reactor with Teflon liner. The chemical reaction can proceed at the temperature higher than the boiling point of the solvent. Under such condition, high pressure can be generated, promoting the reaction and improving the crystallinity of the synthesized NCs [34]. The main advantage of the hydro-/solvothermal strategy is that almost all precursors can dissolve in the solvent at high pressure and temperature. Besides that, the merits of hydro-/solvothermal strategy, including the easy operability, high yield, and low cost, make it an attractive choice for constructing epitaxial heterostructures. As a typical example, Wang et al. reported the epitaxial growth of α-Fe 2 O 3 on CdS nanowires (NWs) via a two-step solvothermal process using N,N-dimethylformamide as solvent and poly(vinylpyrrolidone) as surfactant [35].Even though hydro-/solvothermal strategy has been widely used to prepare epitaxial heterostructures, it has disadvantages as well. Firstly, it is impossible to observe the reaction process in situ since the reaction occurs in a sealed autoclave, making it difficult to propose the growth mechanism. Besides, since the hydro-/solvothermal r...

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Interface control of electronic and optical properties in IV–VI and II–VI core/shell colloidal quantum dots: a review

Cited by 97 publications

References 294 publications

Hot carriers perspective on the nature of traps in perovskites

Hot carriers perspective on the nature of traps in perovskites

Core/Shell Quantum Dots Solar Cells

Wet-Chemical Synthesis and Applications of Semiconductor Nanomaterial-Based Epitaxial Heterostructures

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