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Abstract
Intrinsically flexible near-infrared (NIR) light sources are experiencing rapid growth in recent years. However, NIR light sources with a combination of high-efficiency, long-lifetime, and large-area remain challenging. Here, we realize high-efficiency, long-lifetime and large-area NIR light sources based on organic light-emitting diodes (OLEDs) and NIR-emitting PbS quantum dots (QDs) as color conversion layers. To obtain highly efficient PbS QDs, a unique additive composition comprising KCl and crown ethers is employed, which can significantly passivate trap states in the air and at room temperature, thus improving the photoluminescence quantum efficiency from 24% to 35% in solution and further to 45% in blend films. The well-passivated PbS QD films are then integrated with red OLEDs and the resulting QD-OLEDs exhibit high-performance NIR emission centered at 887 nm, a high external quantum efficiency of 5.2% at a radiance of 10 W sr-1 m-2, and superior operational stability with long lifetime T90 of 188 hours at the current density of 25 mA cm-2, which presents the best result for solution-processed NIR LEDs. We also construct a large-area NIR QD-OLED (5×5 cm2) with desirable uniform emission. This work opens a new avenue to achieve robust large-area NIR light sources for broad applications.
Supplementary materials
Title
Supporting Information for High-efficiency, Long-lifetime and Large-area Near-infrared QD-OLEDs
Description
Table of content:
Section 1. Calculations of inter-dot spacings
Table S1. PLQY and the calculated interdot spacings of blend films.
Table S2. The solution-processed NIR-LEDs devices (including perovskite-based LED and quantum dot-based LED) with published to date with the emission maxima over 800 and the corresponding citations
Figure S1. The absorption spectra of PbS QDs under different injection temperature.
Figure S2. The XPS patterns of Cl 2p signal from QDs with and without KCl and DB-18-crown-6 treatment.
Figure S3. The FTIR spectra of QDs with and without DB-18-crown-6 treatment.
Figure S4. The HR-TEM images of treated PbS QDs with and without KCl and DB-18-crown-6 treatment.
Figure S5. The TEM image of the blend film of PbS QDs and polymers.
Figure S6. The PL decay curve of the blend film and pure film on pulsed excitation with 475 nm light.
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