High-performance crosslinked colloidal quantum-dot light-emitting diodes

Cho, Kyung‐Sang; Lee, Eun Kyung; Joo, Won-Jae; Jang, Eunjoo; Kim, Sang Woo; Lee, Sang Jin; Kwon, Soon‐Jae; Han, Jai Yong; Kim, Byung-Ki; Choi, Byoung Lyong; Kim, Jong Min

doi:10.1038/nphoton.2009.92

Cited by 529 publications

(382 citation statements)

References 19 publications

Supporting

Mentioning

372

Contrasting

Unclassified

Order By: Relevance

“…Lead chloride (98%), sulfur (100%), oleylamine (OLA) lead acetate trihydrate, trioctylphosphine (TOP 90%), bis-(trimethylsilyl) sulde (TMS) 2 S, (technical grade, 70%), cadmium oxide (99%), oleic acid (OA), MAA, 1-octadecene (ODE), tetraethyl orthosilicate (TEOS), acetonitrile, ammonium hydroxide (29%), SnCl 4 , and hydrochloric acid were obtained from Sigma-Aldrich Inc. Hexane, toluene, and ethanol were purchased from Fisher Scientic Company. TiO 2 paste composed of 20 nm sized anatase nanoparticles was purchased from Dyesol (18 NR-T).…”

Section: Methodsmentioning

confidence: 99%

“…Colloidal quantum dots (QDs) have been recently employed in several technologically relevant applications such as photodetectors, 1 light emitting technologies [2][3][4] and excitonic (third generation) solar cells. 5,6 In the latter case, they paved the way for the development of low cost solar cells fabricated through low temperature processes.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Controlling photoinduced electron transfer from PbS@CdS core@shell quantum dots to metal oxide nanostructured thin films

et al. 2014

View full text Add to dashboard Cite

N-type metal oxide solar cells sensitized by infrared absorbing PbS quantum dots (QDs) represent a promising alternative to traditional photovoltaic devices. However, colloidal PbS QDs capped with pure organic ligand shells suffer from surface oxidation that affects the long term stability of the cells.Application of a passivating CdS shell guarantees the increased long term stability of PbS QDs, but can negatively affect photoinduced charge transfer from the QD to the oxide and the resulting photoconversion efficiency (PCE). For this reason, the characterization of electron injection rates in these systems is very important, yet has never been reported. Here we investigate the photoelectron transfer rate from PbS@CdS core@shell QDs to wide bandgap semiconducting mesoporous films using photoluminescence (PL) lifetime spectroscopy. The different electron affinity of the oxides (SiO 2 , TiO 2 and SnO 2 ), the core size and the shell thickness allow us to fine tune the electron injection rate by determining the width and height of the energy barrier for tunneling from the core to the oxide.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Controlling photoinduced electron transfer from PbS@CdS core@shell quantum dots to metal oxide nanostructured thin films

et al. 2014

View full text Add to dashboard Cite

show abstract

“…Having established the double-heterojunction structure that allows high PL quantum yields with narrow linewidths, we now discuss the impact of the staggered band offset of CdS and ZnSe by examining the electroluminescence (EL) performance of DHNRs. LEDs with DHNRs as emitting elements (DHNR LEDs) were fabricated with device design similar to reported core/shell nanocrystal LEDs (C/S LEDs) 9,45,46 . Figure 5a inset shows the schematic of our device structure.…”

Section: Challenges In Synthesismentioning

confidence: 99%

“…7b) suggest that DHNRs are primarily orientated parallel to the device plane. The transport layers and electrodes used here have also been used in C/S LEDs with external quantum efficiencies (EQEs) reaching up to B1.7% for emission wavelength comparable to our DHNR LEDs 9,45,46 . Figure 5a shows the energy band diagram of our DHNR LEDs that should lead to efficient carrier injection to the DHNRs (especially for holes) owing to the presence of the double heterojunction.…”

Section: Challenges In Synthesismentioning

confidence: 99%

Double-heterojunction nanorods

et al. 2014

View full text Add to dashboard Cite

As semiconductor heterostructures play critical roles in today's electronics and optoelectronics, the introduction of active heterojunctions can impart new and improved capabilities that will enable the use of solution-processable colloidal quantum dots in future devices. Such heterojunctions incorporated into colloidal nanorods may be especially promising, since the inherent shape anisotropy can provide additional benefits of directionality and accessibility in band structure engineering and assembly. Here we develop doubleheterojunction nanorods where two distinct semiconductor materials with type II staggered band offset are both in contact with one smaller band gap material. The double heterojunction can provide independent control over the electron and hole injection/ extraction processes while maintaining high photoluminescence yields. Light-emitting diodes utilizing double-heterojunction nanorods as the electroluminescent layer are demonstrated with low threshold voltage, narrow bandwidth and high efficiencies.

show abstract

“…1 High efficiencies are especially important for application of QDs as luminescent biolabels, 2 in QD lasers, 3 in spectral converters for warm white LEDs, 4,5 electroluminescent devices, 6 and solar concentrators. 7 Luminescence efficiencies are strongly temperature-dependent.…”

mentioning

confidence: 99%

High-Temperature Luminescence Quenching of Colloidal Quantum Dots

et al. 2012

View full text Add to dashboard Cite

A high luminescence efficiency is an important property of colloidal quantum dots (QDs), and quantum yields higher than 90% have been reported for coreÀshell QDs. 1 High efficiencies are especially important for application of QDs as luminescent biolabels, 2 in QD lasers, 3 in spectral converters for warm white LEDs, 4,5 electroluminescent devices, 6 and solar concentrators. 7 Luminescence efficiencies are strongly temperature-dependent. 8 Extensive temperature-dependent luminescence studies for colloidal QDs have been conducted at cryogenic temperatures (0.3À300 K). 9À15 In this temperature region, interesting effects were observed, including a prolonged lifetime below 20 K related to brightÀdark state splitting, 11,16 thermally activated quenching due to surface defect states, 9,10,17 and temperature antiquenching assigned to a phase transition in the capping layer. 14,15 However, the luminescence properties of QDs above room temperature (RT) are hardly investigated, and yet, for most applications in luminescent devices, the working temperature is higher than 300 K. An interesting example is the recent application of QDs as color converters in warm-white LEDs, 18 in which QDs serve as narrow band red emitters under excitation with blue light from a (In,Ga)N LED. The narrow emission bandwidth renders QDs superior to classical phosphors based on broad band emission from luminescent ions. 19 In high-power LEDs for general lighting applications, the heat generated in the pÀn junction and phosphor converter layer leads to temperatures as high as 150À200°C in the layer applied on top of the blue diode. 20 To avoid these high temperatures, the QD phosphor layer can be placed in a more remote configuration. Still, temperatures in such a configuration are expected to be well above 50°C due to heat dissipation of the QDs themselves (excess energy from converting the blue into red light). Clearly, the quenching of QD luminescence at elevated temperatures is relevant for application of QDs in luminescent devices, and a better insight in the quenching behavior is needed.Despite its importance, research on luminescence temperature quenching above RT is very limited for QDs. It is theoretically expected for a QD to have a very high luminescence quenching temperature (T q ). Three generally accepted mechanisms for thermal quenching involve thermally activated crossover from the excited state to the ground state, multiphonon relaxation, and thermally activated photoionization. The first mechanism is generally depicted in a simple configurational coordinate diagram. 8,21 The energy difference between the minimum * Address correspondence to a.meijerink@uu.nl.Received for review July 18, 2012 and accepted September 14, 2012. Published online 10.1021/nn303217qABSTRACT Thermal quenching of quantum dot (QD) luminescence is important for application in luminescent devices. Systematic studies of the quenching behavior above 300 K are, however, lacking. Here, high-temperature (300À500 K) luminescence studies are reported for highly ef...

show abstract

High-performance crosslinked colloidal quantum-dot light-emitting diodes

Cited by 529 publications

References 19 publications

Controlling photoinduced electron transfer from PbS@CdS core@shell quantum dots to metal oxide nanostructured thin films

Controlling photoinduced electron transfer from PbS@CdS core@shell quantum dots to metal oxide nanostructured thin films

Double-heterojunction nanorods

High-Temperature Luminescence Quenching of Colloidal Quantum Dots

Contact Info

Product

Resources

About