A monolithic white laser

Fan, Fan; Türkdoğan, Sunay; Liu, Zhicheng; Shelhammer, David; Ning, Cun‐Zheng

doi:10.1038/nnano.2015.149

Cited by 210 publications

(223 citation statements)

References 47 publications

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“…In principle, the emission wavelength of the red and blue parts is tunable by varying the conversion degree, and the relative intensity of each color can be tuned by varying the pixel size of each segment. Such color-tunable perovskite heterostructures provide an ideal platform for full-color displays and solid-state lighting (30)(31)(32)(33). The spectral scan on the three-color nanowire shows two sharp junctions at the interfaces (SI Appendix, Fig.…”

Section: Resultsmentioning

confidence: 99%

Spatially resolved multicolor CsPbX ₃ nanowire heterojunctions via anion exchange

Dou

Lai

Kley

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

203

224

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Halide perovskites are promising semiconductor materials for solutionprocessed optoelectronic devices. Their strong ionic bonding nature results in highly dynamic crystal lattices, inherently allowing rapid ion exchange at the solid-vapor and solid-liquid interface. Here, we show that the anion-exchange chemistry can be precisely controlled in single-crystalline halide perovskite nanomaterials when combined with nanofabrication techniques. We demonstrate spatially resolved multicolor CsPbX 3 (X = Cl, Br, I, or alloy of two halides) nanowire heterojunctions with a pixel size down to 500 nm with the photoluminescence tunable over the entire visible spectrum. In addition, the heterojunctions show distinct electronic states across the interface, as revealed by Kelvin probe force microscopy. These perovskite heterojunctions represent key building blocks for high-resolution multicolor displays beyond current state-of-the-art technology as well as high-density diode/transistor arrays.nanowire | halide perovskite | anion exchange | heterojunction S ignificant research efforts are currently directed toward lead halide-based perovskites, owing to their unusual optoelectronic and photovoltaic properties (1-5). In addition to polycrystalline thin films, various solution-based synthetic routes toward low-dimensional nanostructures of halide perovskites have been recently demonstrated, with control over size, shape, mixed halide composition, and consequently their band gap and emission wavelength (6-10). Interestingly, it has been shown that these materials, both in bulk and in nanocrystalline form, can undergo fast anion-exchange reactions at the solid-liquid or solid-gas interface, with a fine-tuning of the chemical composition and electronic properties (11)(12)(13)(14). The fast ion-exchange kinetics in halide perovskite are related to the low defect formation energy and the existence of a large number of vacancies, which make the ions highly mobile in the crystal lattice (15). As a result, the anionexchange reaction in halide perovskites favors forming homogeneous alloys instead of any kind of heterostructures as commonly observed in II-VI semiconductor compounds. If the exchange reaction can be localized at particular positions, then it is possible to produce substrates with well-defined patterns of semiconductor heterojunctions (16)(17)(18)(19)(20). The physical properties (optical, electrical, magnetic, etc.) of the heterostructure are fundamentally interesting, and the patterned semiconductor heterojunctions are essential for the fabrication of large-scale high-density integrated electronic and photonic devices.Compared with perovskite polycrystalline thin films and quantum dots, single-crystalline nanowires provide an ideal platform for producing and studying heterojunctions via ion-exchange chemistry because of the absence of grain boundaries and the unique one-dimensional geometry (21-24). The relatively thin diameter of the nanowire ensures rapid ion exchange in the radial direction, whereas the micrometer scale l...

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Section: Resultsmentioning

confidence: 99%

Spatially resolved multicolor CsPbX ₃ nanowire heterojunctions via anion exchange

Dou

Lai

Kley

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

203

224

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“…Finally, the model that we developed can lead to the rational design of QDs with controlled radiative and nonradiative rates, as well as fast color-switchable 46−49 or white-light lasers. 10,50−52 Such devices, ideally of small dimensions, can drive novel techniques for biological and chemical sensing, 53 laser imaging and displays, 54 and wavelength-division multiplexing. 55,56 …”

mentioning

confidence: 99%

Colloidal-Quantum-Dot Ring Lasers with Active Color Control

et al. 2018

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To improve the photophysical performance of colloidal quantum dots for laser applications, sophisticated core/shell geometries have been developed. Typically, a wider bandgap semiconductor is added as a shell to enhance the gain from the quantum-dot core. This shell is designed to electronically isolate the core, funnel excitons to it, and reduce nonradiative Auger recombination. However, the shell could also potentially provide a secondary source of gain, leading to further versatility in these materials. Here we develop high-quality quantum-dot ring lasers that not only exhibit lasing from both the core and the shell but also the ability to switch between them. We fabricate ring resonators (with quality factors up to ∼2500) consisting only of CdSe/CdS/ZnS core/shell/shell quantum dots using a simple template-stripping process. We then examine lasing as a function of the optical excitation power and ring radius. In resonators with quality factors >1000, excitons in the CdSe cores lead to red lasing with thresholds at ∼25 μJ/cm2. With increasing power, green lasing from the CdS shell emerges (>100 μJ/cm2) and then the red lasing begins to disappear (>250 μJ/cm2). We present a rate-equation model that can explain this color switching as a competition between exciton localization into the core and stimulated emission from excitons in the shell. Moreover, by lowering the quality factor of the cavity we can engineer the device to exhibit only green lasing. The mechanism demonstrated here provides a potential route toward color-switchable quantum-dot lasers.

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“…[1][2][3][4][5] The interface of the heterojunction is important and greatly influenced by the effect of an energy state discontinuity. The piezoelectric effect is the coupling of piezoelectric polarization (P pz ) and the intrinsic electric field, which can be used to tune charge transportation of corresponding materials.…”

Section: Introductionmentioning

confidence: 99%

Effects of Piezoelectric Potential of ZnO on Resistive Switching Characteristics of Flexible ZnO/TiO2 Heterojunction Cells

Zhou

et al. 2017

Journal of Elec Materi

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Flexible resistance random access memory (ReRAM) devices with a heterojunction structure of PET/ITO/ZnO/TiO 2 /Au were fabricated on polyethylene terephthalate/indium tin oxide (PET/ITO) substrates by different physical and chemical preparation methods. X-ray diffraction, scanning electron microscopy and atomic force microscopy were carried out to investigate the crystal structure, surface topography and cross-sectional structure of the prepared films. X-ray photoelectron spectroscopy was also used to identify the chemical state of Ti, O and Zn elements. Theoretical and experimental analyses were conducted to identify the effect of piezoelectric potential of ZnO on resistive switching characteristics of flexible ZnO/TiO 2 heterojunction cells. The results showed a pathway to enhance the performance of ReRAM devices by engineering the interface barrier, which is also feasible for other electronics, optoelectronics and photovoltaic devices.

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A monolithic white laser

Cited by 210 publications

References 47 publications

Spatially resolved multicolor CsPbX ₃ nanowire heterojunctions via anion exchange

Spatially resolved multicolor CsPbX ₃ nanowire heterojunctions via anion exchange

Colloidal-Quantum-Dot Ring Lasers with Active Color Control

Effects of Piezoelectric Potential of ZnO on Resistive Switching Characteristics of Flexible ZnO/TiO2 Heterojunction Cells

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A monolithic white laser

Cited by 210 publications

References 47 publications

Spatially resolved multicolor CsPbX 3 nanowire heterojunctions via anion exchange

Spatially resolved multicolor CsPbX 3 nanowire heterojunctions via anion exchange

Colloidal-Quantum-Dot Ring Lasers with Active Color Control

Effects of Piezoelectric Potential of ZnO on Resistive Switching Characteristics of Flexible ZnO/TiO2 Heterojunction Cells

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Spatially resolved multicolor CsPbX ₃ nanowire heterojunctions via anion exchange

Spatially resolved multicolor CsPbX ₃ nanowire heterojunctions via anion exchange