Performance of Spherical Quantum Well Down Converters in Solid State Lighting

Abstract

We report the color conversion performance of amber and red emitting quantum dots on InGaN solid state lighting (SSL) light emitting diode (LED) packages. Spherical quantum well (SQW) architectures (CdS/CdSe1-xSx/CdS) were finely adjusted using a library of thio-and selenourea synthesis reagents and high throughput synthesis robotics. CdS/CdSe1-xSx particles with narrow luminescence bands were coated with thick CdS shells (thickness = 1.4 -7.5 nm) to achieve photoluminescence quantum yields (PLQY) up to 88% at amber and red emission wavelengths (max = 600 -642nm, FWHM < 45 nm). The photoluminescence from SQWs encapsulated in silicone and deposited on LED packages was monitored under accelerated aging conditions (oven temperature = 85 C, relative humidity = 5 -85%, blue optical power density = 3 -45 W/cm 2 ) by monitoring the red photon output over several hundred hours of continuous operation. Growth of a ZnS shell on the SQW surface increases the stability under long-term operation but also reduces the PLQY, especially of SQWs with thick CdS shells. The results illustrate that the outer ZnS shell layer is key to optimizing the PLQY and the long-term stability of QDs during operation on SSL packages.

Active Learning of Ligands That Enhance Perovskite Nanocrystal Luminescence

“…Our approach is highly generalizable as our model can be retrained with other types of NCs using other application-relevant outcomes, such as luminescence lifetime, PLQY droop, colloidal stability, and spectral shifts over time . Thus, our HT-AL workflow can benefit a wide range of NCs, particularly semiconductor QDs, , lanthanide-doped upconverting nanoparticles, ,− plasmonic metal nanoparticles, and many other materials with optical properties known to be sensitive to surface ligands. These workflows will enable further insight into the optical stability of NCs, providing a path toward mapping the complex ligand space across a wide range of nanoparticles.…”

Synthesis of graded CdS1−xSex nanoplatelet alloys and heterostructures from pairs of chalcogenoureas with tailored conversion reactivity

“…8 For these reasons, precisely tailored alloys with graded compositions could reach new levels of luminescence performance. 9,10…”

A 1D helical eco-friendly Mn(II) halide coordination polymer: Luminescent properties involving resonant energy transfer and magnetic characterization

“…Being made through yellow phosphor coated blue LEDs or red, green and blue phosphor integrated UV LEDs. The currently commercialized SSLs are commonly white light-emitting diodes (LEDs) [1][2][3][4] . However, these strategies used to achieve white emission have many drawbacks, such as reduced self-absorption efficiency, changes in emission color, attenuation of individual components, and reduced color rendering.…”