Electroluminescent Guest@MOF Nanoparticles for Thin Film Optoelectronics and Solid‐State Lighting

Abstract

Light‐emitting diodes (LEDs) are an efficient source of lighting, with many commercial applications like general illumination, camera flashes, phone or laptop displays, and TV screens. However, they present certain limitations, including low‐quality color rendition, and the use of expensive/toxic rare‐earth elements. There is therefore an urgent need for the development of improved luminescent materials free of rare earths. Luminescent metal–organic framework (LMOF) materials are promising candidates for photonics devices. Most MOF‐LEDs reported are of the down‐converter type, where UV or blue LED are coated with LMOFs, however there is limited progress in the development of LED using LMOFs as the electroluminescent layer. Herein, it is reported a novel Guest@MOF composite synthesized by encapsulating a semiconducting Gaq3 metal complex [gallium(III) tris(8‐hydroxyquinolinato)], into the ZIF‐8 pore [Zn (2‐methylimidazolate)2], yielding a green‐yellowish luminescent material exhibiting a relatively high quantum yield of 15% upon photoexcitation. Subsequently, a down‐converter LED comprising 405‐nm violet LED coated with Gaq3@ZIF‐8, yielding a white MOF‐LED is shown. Then the use of Gaq3@ZIF‐8 as an electroluminescent layer in a hybrid‐LED, achieving an orange‐yellowish light emitting device is demonstrated. This work reveals the potential of LMOFs for next‐generation LED technology, by exploiting the Guest@MOF concept to enable electroluminescent applications.

Electrospun rhodamine@MOF/polymer luminescent fibers with a quantum yield of over 90%

“…The physical and chemical functions of MOFs can be enhanced further by leveraging the concept of “Guest@MOF” system ( Allendorf et al., 2015 ), yielding luminescent composite materials attractive for solid-state lighting and optical sensing applications ( Zhang et al., 2020 ; Gutiérrez et al., 2020 ; Chaudhari et al., 2017 ; Lin et al., 2019 ). This “guest-host” system takes advantage of the porous nature of MOF (serving as a “host”) to confine luminescent molecules (as a “guest”) into the nanoscale pores or by trapping them within the extended MOF structures.…”

Interrogating the Behaviour of a Styryl Dye Interacting with a Mesoscopic 2D-MOF and Its Luminescent Vapochromic Sensing

“…Three DCM/Al-ITQ-HB composites of different loadings were prepared using different concentrations of DCM dye: 5 × 10 −6 , 1 × 10 −4 , and 1 × 10 −3 M. Considering the synthetic procedure of these hybrid composites (see Section 3 ) where the solvent is evaporated and the final hybrid composite sample is not washed, we can envisage that most of DCM molecules will be adsorbed on the MOF’s surface. Indeed, it has been described that a proper washing is necessary for removing the molecules adhered to the MOFs‘ surface, meaning that when the hybrid material is not properly washed, most of the molecules will be attached onto the MOF’s surface [ 46 , 47 , 48 ]. The colour of the obtained samples (DCM/Al-ITQ-HB- d , d = diluted; DCM/Al-ITQ-HB- i, i = intermediate; DCM/Al-ITQ-HB- c , c = concentrated) varies from light to vibrant orange when the initial dye concentration increases ( Figure 1 A).…”

Encapsulation of Dyes in Luminescent Metal-Organic Frameworks for White Light Emitting Diodes

“…Benefiting from the host-guest shielding effect, the stability of hybrid materials can be further improved. Tan et al [39] conducted a long-term material stability test on dye-encapsulated MOF Gaq3@ZIF-8, and the results showed that after 8 months, not only the structure of ZIF-8 could remain stable with Gaq3 dye being encapsulated, but also the absolute QY of Gaq3@ZIF-8 (15%) was exactly the same as prepared, which demonstrates that when trapping Gaq3 in ZIF-8 pores, the host can act as a shield to protect Gaq3 from photodegradation. A WLED emitting uniform white light could be obtained by coating Gaq3@ZIF-8 on a blue LED.…”