A Red-Emitting Cu(I)–Halide Cluster Phosphor with Near-Unity Photoluminescence Efficiency for High-Power wLED Applications

Abstract

Solid-state lighting technology, where light-emitting diodes (LEDs) are used for energy conversion from electricity to light, is considered a next-generation lighting technology. One of the significant challenges in the field is the synthesis of high-efficiency phosphors for designing phosphor-converted white LEDs under high flux operating currents. Here, we reported the synthesis, structure, and photophysical properties of a tetranuclear Cu(I)–halide cluster phosphor, [bppmCu2I2]2 (bppm = bisdiphenylphosphinemethane), for the fabrication of high-performance white LEDs. The PL investigations demonstrated that the red emission exhibits a near-unity photoluminescence quantum yield at room temperature and unusual spectral broadening with increasing temperature in the crystalline state. Considering the excellent photophysical properties, the crystalline sample of [bppmCu2I2]2 was successfully applied for the fabrication of phosphor-converted white LEDs. The prototype white LED device exhibited a continuous rise in brightness in the range of a high bias current (100–1000 mA) with CRI as high as 84 and CCT of 5828 K, implying great potential for high-quality white LEDs.

Thermally Activated Delayed Fluorescence (TADF)‐active Coinage‐metal Sulfide Clusters for High‐resolution X‐ray Imaging

“…Owing to the d 10 electronic configuration of Cu I and Ag I and discrete energy levels, coinage‐metal clusters make a figure in the fields of bioimaging, circularly polarized luminescence and bl‐labeling [20–25] . However, only a few polynuclear coinage‐metal clusters, rather rare silver clusters, behave high photoluminescence quantum yields ( Φ PL >80 %) due to environmental susceptibility of silver [26–28] . Some bright emissions were verified to originate from the assistance of TADF [29a] .…”

“…[20][21][22][23][24][25] However, only a few polynuclear coinagemetal clusters, rather rare silver clusters, behave high photoluminescence quantum yields (Φ PL > 80 %) due to environmental susceptibility of silver. [26][27][28] Some bright emissions were verified to originate from the assistance of TADF. [29a] Nevertheless, TADF-assisted silver clusters scintillators have not been studied so far.…”

Suppressing the Thermal Quenching Effect via a Cluster Conformer in Copper(I)–Iodide Coordination Polymeric Phosphors for High-Power White LED Lighting

“…Recently, the copper­(I) complexes have received wide attention for their well-defined structure and photophysical properties. − The study in this field has obtained an important momentum in the past decade because this type of complex can be potential candidates for application in organic light-emitting diodes (OLEDs) or white light-emitting diodes (WLEDs). − By virtue of an efficient triplet emission and/or thermally activated delayed fluorescence, − Cu­(I) complexes have been regarded as a low-cost alternative to noble metal-based emitting materials . As the most representative copper­(I) emitters, [Cu 4 X 4 ]-type (X = Cl, Br, or I) clusters have been reported to typically exhibit two conformers (cubane and staircase). − It is well-recognized that the cuprophilic Cu···Cu interaction plays a crucial role in the luminescence origin of the cluster system. − Generally, the [Cu 4 I 4 ] staircase-like structures emit their photoluminescence via the excited state of (X+M)­LCT, while the [Cu 4 I 4 ] cubanes emit via the cluster-center ( 3 CC) transition. , The process of (X+M)­LCT is normally associated with the weak Cu···Cu interactions; however, the 3 CC transition frequently occurs in the case of the strong Cu···Cu interactions in copper­(I) iodide clusters, especially in those of cubane [Cu 4 I 4 ] clusters. In some cases, this type of cluster emits intriguing thermochromic luminescence from its temperature-dependent triplet excited states, i.e ., 3 CC and 3 (X+M)­LCT.…”