Enhancement of the External Quantum Efficiency of a Silicon Quantum Dot Light-Emitting Diode by Localized Surface Plasmons

Purpose This study aims to focus on roughening N-face (backside) GaN substrate prior to GaN-on-GaN light-emitting diode (LED) growth as an attempt to improve the LED performance. Design/methodology/approach The N-face of GaN substrate was roughened by three different etchants; ammonium hydroxide (NH4OH), a mixture of NH4OH and H2O2 (NH4OH: H2O2) and potassium hydroxide (KOH). Hexagonal pyramids were successfully formed on the surface when the substrate was subjected to the etching in all cases. Findings Under 30 min of etching, the highest density of pyramids was obtained by NH4OH: H2O2 etching, which was 5 × 109 cm–2. The density by KOH and NH4OH etchings was 3.6 × 109 and 5 × 108 cm–2, respectively. At standard operation of current density at 20 A/cm2, the optical power and external quantum efficiency of the LED on the roughened GaN substrate by NH4OH: H2O2 were 12.3 mW and 22%, respectively, which are higher than its counterparts. Originality/value This study demonstrated NH4OH: H2O2 is a new etchant for roughening the N-face GaN substrate. The results showed that such etchant increased the density of the pyramids on the N-face GaN substrate, which subsequently resulted in higher optical power and external quantum efficiency to the LED as compared to KOH and NH4OH.

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Quantum Dot LEDs: Over 30% External Quantum Efficiency Light‐Emitting Diodes by Engineering Quantum Dot‐Assisted Energy Level Match for Hole Transport Layer (Adv. Funct. Mater. 33/2019)

Advanced Functional Materials ◽

10.1002/adfm.201970226 ◽

2019 ◽

Vol 29 (33) ◽

pp. 1970226 ◽

Cited By ~ 2

Author(s):

Jiaojiao Song ◽

Ouyang Wang ◽

Huaibin Shen ◽

Qingli Lin ◽

Zhaohan Li ◽

...

Keyword(s):

Energy Level ◽

Quantum Dot ◽

Quantum Efficiency ◽

External Quantum Efficiency ◽

Light Emitting Diodes ◽

Hole Transport ◽

Transport Layer ◽

Hole Transport Layer ◽

Light Emitting

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Tricomponent Exciplex Emitter Realizing over 20% External Quantum Efficiency in Organic Light‐Emitting Diode with Multiple Reverse Intersystem Crossing Channels

Advanced Science ◽

10.1002/advs.201801938 ◽

2019 ◽

Vol 6 (14) ◽

pp. 1801938 ◽

Cited By ~ 10

Author(s):

Ming Zhang ◽

Wei Liu ◽

Cai‐Jun Zheng ◽

Kai Wang ◽

Yi‐Zhong Shi ◽

...

Keyword(s):

Quantum Efficiency ◽

External Quantum Efficiency ◽

Light Emitting Diode ◽

Intersystem Crossing ◽

Light Emitting ◽

Organic Light Emitting Diode ◽

Organic Light

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Silicon Quantum Dot Light Emitting Diode at 620 nm

Micromachines ◽

10.3390/mi10050318 ◽

2019 ◽

Vol 10 (5) ◽

pp. 318 ◽

Cited By ~ 8

Author(s):

Hiroyuki Yamada ◽

Naoto Shirahata

Keyword(s):

Quantum Dot ◽

High Performance ◽

Light Emitting Diode ◽

Optically Active ◽

Driving Voltage ◽

Device Structure ◽

Light Emitting ◽

Naked Eye ◽

Turn On ◽

Silicon Quantum Dot

Here we report a quantum dot light emitting diode (QLED), in which a layer of colloidal silicon quantum dots (SiQDs) works as the optically active component, exhibiting a strong electroluminescence (EL) spectrum peaking at 620 nm. We could not see any fluctuation of the EL spectral peak, even in air, when the operation voltage varied in the range from 4 to 5 V because of the possible advantage of the inverted device structure. The pale-orange EL spectrum was as narrow as 95 nm. Interestingly, the EL spectrum was narrower than the corresponding photoluminescence (PL) spectrum. The EL emission was strong enough to be seen by the naked eye. The currently obtained brightness (∼4200 cd/m2), the 0.033% external quantum efficiency (EQE), and a turn-on voltage as low as 2.8 V show a sufficiently high performance when compared to other orange-light-emitting Si-QLEDs in the literature. We also observed a parasitic emission from the neighboring compositional layer (i.e., the zinc oxide layer), and its intensity increased with the driving voltage of the device.

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