Abstract
A detailed study of the pump-intensity dependent characteristics of an all-inorganic CsPbBr3-in-Cs4PbBr6 quantum dot (QD) color converter are reported. This is an attractive material to color convert UV/blue GaN optical pump sources for digital lighting applications, e.g. visible light communications (VLC). It demonstrates narrow spectral emission (522 nm peak emission and < 20 nm full-width-at-half-maximum), invariant with the pump power density (from 0 to 7.15 kW/cm2). The optical bandwidth increases, from 10 MHz at 300 µW/cm2, up to 22 MHz at 3 W/cm2, and 41 MHz at 7.15 kW/cm2. This acceleration of the emission is ascribed to both an increase of the radiative decay rate in the low-pump-density regime, and to the emergence of non-radiative pathways at higher pump density. The higher bandwidth at high-pump density enables a 30% increase in the data rate of a free space VLC link using this color converter.
Highlights
Luminophores pumped by efficient blue GaN lasers or LEDs are enabling solid-state optical sources for displays, lighting and illumination, and they have a role to play in emerging digital lighting applications, such as visible light communications (VLC) [1,2]
The most plausible explanation is the formation of CsPbBr3 quantum dot (QD) within the Cs4PbBr6 host, and we refer to this nanocomposite system as ‘CsPbBr3-in-Cs4PbBr6’ QDs in the following discussion
For the first time to our knowledge, CsPbBr3 QDs in Cs4PbBr6 crystals were used as a fast color converter, with emission at 520 nm, for VLC
Summary
Luminophores pumped by efficient blue GaN lasers or LEDs are enabling solid-state optical sources for displays, lighting and illumination, and they have a role to play in emerging digital lighting applications, such as visible light communications (VLC) [1,2] In this context, alternatives to phosphors, typically used for color conversion of GaN devices, are being explored to address the bandwidth issue of phosphor-converted sources that severely limits their capability [3,4]. As a truly all-inorganic system, CsPbBr3-in-Cs4PbBr6 QDs promise enhanced stability compared to colloidal quantum dots because the CsPbBr3 QDs are ‘ligand-free’ and inherently encapsulated in a higher-bandgap semiconductor material This material was shown to have high thermal stability when demonstrated as a laser gain material [19]. To our knowledge, it has never been studied in that context prior to this work
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