Title: Droop-Free Colloidal Quantum Dot Light-Emitting Diodes

Abstract

Colloidal semiconductor quantum dots (QDs) are a highly promising materials platform for implementing solution-processable light-emitting diodes (LEDs). They combine high photostability of traditional inorganic semiconductors with chemical flexibility of molecular systems, which makes them well-suited for large-area applications such as television screens, solid-state lighting, and outdoor signage. Additional beneficial features include size-controlled emission wavelengths, narrow bandwidths, and nearly perfect emission efficiencies. State-of-the-art QD-LEDs exhibit high internal quantum efficiencies approaching unity. However, these peak values are observed only at low current densities (J) and correspondingly low brightnesses, whereas at higher J, the efficiency usually exhibits a quick roll-off. This efficiency droop limits achievable brightness levels and decreases device longevity due to excessive heat generation. We demonstrate QD-LEDs operating with high internal efficiencies (up to 70%) virtually droop-free up to unprecedented brightness of >100,000 cd m^–2 (at ~500 mA cm^–2). This exceptional performance is derived from specially engineered QDs that feature a compositionally graded interlayer and a final barrier layer. This QD design allows for improved balance between electron and hole injections combined with considerably suppressed Auger recombination, which helps mitigate efficiency losses due to charge imbalance at high currents. Finally, these results indicate a significant potential of newly developed QDs asmore » enablers of future ultrabright, highly efficient devices for both indoor and outdoor applications.« less

Authors:

Lim, Jaehoon  ^[1];

• Search DOE PAGES for author "Lim, Jaehoon"
• Search DOE PAGES for ORCID "0000-0003-2623-3550"

Park, Young -Shin  ^[2];

• Search DOE PAGES for author "Park, Young -Shin"
• Search DOE PAGES for ORCID "0000-0003-4204-1305"

Wu, Kaifeng  ^[3];

• Search DOE PAGES for author "Wu, Kaifeng"
• Search DOE PAGES for ORCID "0000-0002-1047-6606"

Yun, Hyeong Jin  ^[3];

• Search DOE PAGES for author "Yun, Hyeong Jin"
• Search DOE PAGES for ORCID "0000-0002-8401-8886"

Klimov, Victor I.  ^[3]

• Search DOE PAGES for author "Klimov, Victor I."
• Search DOE PAGES for ORCID "0000-0003-1158-3179"

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+ Show Author Affiliations

1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Ajou Univ., Suwon (Korea, Republic of). Dept. of Chemical Engineering. Dept. of Energy System Research
2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Univ. of New Mexico, Albuquerque, NM (United States). Center for High Technology Materials
3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

Publication Date:

Mon Sep 10 00:00:00 EDT 2018

Research Org.:

Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES); LANL Laboratory Directed Research and Development (LDRD) Program

OSTI Identifier:

1477674

Report Number(s):

LA-UR-18-28788
Journal ID: ISSN 1530-6984

Grant/Contract Number:  

AC52-06NA25396

Resource Type:

Accepted Manuscript

Journal Name:

Nano Letters

Additional Journal Information:

Journal Volume: 18; Journal Issue: 10; Journal ID: ISSN 1530-6984

Publisher:

American Chemical Society

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Nanocrystal quantum dots Light emitting diode Droop-free