163 research outputs found
Enhancing the Overall Performances of Blue Light-Emitting Electrochemical Cells by Using an Electron-Injecting/Transporting Ionic Additive
Light-emitting
electrochemical cells (LECs) have emerged as a promising emissive
thin-film technology for next-generation solid-state lighting. However,
blue LECs show low performances, which has remained a bottleneck for
the fabrication of white LECs for lighting applications. Here, we
demonstrate a remarkable enhancement of overall device performance
for blue LECs by using an electron-injecting/transporting ionic additive,
that is, [ZnÂ(bpy)<sub>3</sub>]Â(PF<sub>6</sub>)<sub>2</sub> (bpy is
2.2′-bipyridine, PF<sub>6</sub><sup>–</sup> is hexafluorophosphate).
It is revealed that adding [ZnÂ(bpy)<sub>3</sub>]Â(PF<sub>6</sub>)<sub>2</sub> into the active layers of blue LECs accelerates the device
response, simultaneously enhances the brightness and efficiency, reduces
the efficiency roll-offs, significantly improves the blue color stability
upon the continuous electrical operation, and enhances the device
operational stability at optimized conditions. The remarkable enhancement
of the overall device performance upon adding [ZnÂ(bpy)<sub>3</sub>]Â(PF<sub>6</sub>)<sub>2</sub> results from facilitated electron injection/transport
and thus more balanced electron–hole recombination and more
centered recombination zone, as well as the reduction of phosphorescence
concentration quenching in the LECs. The work demonstrates for the
first time that the use of electron-injecting/transporting ionic additives
such as [ZnÂ(bpy)<sub>3</sub>]Â(PF<sub>6</sub>)<sub>2</sub> is a facile
yet effective strategy to remarkably boost the overall performances
of blue LECs
Fitted curves of the spectrum from the 70° Bi<sub>2</sub>Te<sub>3</sub> tip, with the fitted sub-peaks of tip plasmons (green), bulk/substrate emission (light blue), and edge plasmons (dark blue), respectively.
The fitted peak position of tip plasmons is 413.61 nm. (TIF)</p
S1 Data -
Bi2Te3, as a topological insulator, is able to support plasmonic emission in the visible spectral range. Thin Bi2Te3 flakes can be exfoliated directly from a Bi2Te3 crystal, and the shape of Bi2Te3 flakes can be further modified by focused ion beam milling. Therefore, we have designed a Bi2Te3 triangular antenna with distinct tip angles for the application of plasmonic resonance. The plasmonic emission of the Bi2Te3 triangular antenna is excited and investigated by cathodoluminescence in the scanning electron microscope. Enhanced tip plasmons have been observed from distinct tips with angles of 20º, 36º, 54º, 70º, and 90º, respectively. Due to the confinement of geometric boundaries for oscillating charges, the resonant peak position of tip plasmon with a smaller angle has a blue shift. Moreover, the dependence of plasmonic behavior on the excitation position has been discovered as well. This research provides a unique approach to fabricate Bi2Te3 nanostructures and manipulate the corresponding plasmonic properties.</div
Fitted curves of the spectrum from the 20° Bi<sub>2</sub>Te<sub>3</sub> tip, with the fitted sub-peaks of tip plasmons (green), bulk/substrate emission (light blue), and edge plasmons (dark blue), respectively.
The fitted peak position of tip plasmons is 377.56 nm. (TIF)</p
CL spectra excited at four spots along the angle bisector of the 36° tip.
Excitation locations are shown in the inserted SEM image. The color of each curve matches with the color of excitation spots.</p
Fitted curves of the spectrum from the 54° Bi<sub>2</sub>Te<sub>3</sub> tip, with the fitted sub-peaks of tip plasmons (green), bulk/substrate emission (light blue), and edge plasmons (dark blue), respectively.
The fitted peak position of tip plasmons is 401.58 nm. (TIF)</p
Schematic of the CL characterization process accompanied inside a SEM chamber.
Schematic of the CL characterization process accompanied inside a SEM chamber.</p
(a) EDX spectrum of the same Bi<sub>2</sub>Te<sub>3</sub> flake; (b) CL spectra collected from the center of the Bi<sub>2</sub>Te<sub>3</sub> flake and the substrate.
(a) EDX spectrum of the same Bi2Te3 flake; (b) CL spectra collected from the center of the Bi2Te3 flake and the substrate.</p
S1 File -
Bi2Te3, as a topological insulator, is able to support plasmonic emission in the visible spectral range. Thin Bi2Te3 flakes can be exfoliated directly from a Bi2Te3 crystal, and the shape of Bi2Te3 flakes can be further modified by focused ion beam milling. Therefore, we have designed a Bi2Te3 triangular antenna with distinct tip angles for the application of plasmonic resonance. The plasmonic emission of the Bi2Te3 triangular antenna is excited and investigated by cathodoluminescence in the scanning electron microscope. Enhanced tip plasmons have been observed from distinct tips with angles of 20º, 36º, 54º, 70º, and 90º, respectively. Due to the confinement of geometric boundaries for oscillating charges, the resonant peak position of tip plasmon with a smaller angle has a blue shift. Moreover, the dependence of plasmonic behavior on the excitation position has been discovered as well. This research provides a unique approach to fabricate Bi2Te3 nanostructures and manipulate the corresponding plasmonic properties.</div
(a) SEM image and (b-d) EDX maps of the Bi<sub>2</sub>Te<sub>3</sub> triangular nanoflake with three different angles on a Si substrate.
(a) SEM image and (b-d) EDX maps of the Bi2Te3 triangular nanoflake with three different angles on a Si substrate.</p
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