Michael Y. Wong

• PhD (Chemistry), University of St Andrews
• Synthetic Chemist at Huntsman Corporation (Switzerland)

Most silicone polymers are linear compounds derived from dimethylsiloxane (D) monomers; the incorporation of tri- (T) and tetra-functional (Q) monomers usually leads to elastomers. MQ or MT resins, high value materials used as reinforcing agents, are exceptions in that they are very highly branched, and highly reticulated but remain mobile and flui...

The current paradigm in polymer chemistry increasingly involves controlled syntheses with better structural control and, consequently, products with narrow ranges of properties. Traditionally, silicone polymers are prepared under equilibrating conditions to give broad mixtures. The alternative, kinetically controlled ring opening polymerization at...

Aiming to develop efficient blue-emitting thermally activated delayed fluorescence (TADF) compounds, we have designed and synthesized derivatives of the well-known sky-blue emitter 2CzPN that contain electron-accepting phosphine chalcogenide groups to...

Thermally activated delayed fluorescence (TADF) relies on a small energy gap between the emissive singlet and the nonemissive triplet state, obtained by reducing the wave function overlap between donor and acceptor moieties. Efficient emission, however, requires maintaining a good oscillator strength, which is itself based on sufficient overlap of...

Thermally activated delayed fluorescence (TADF) relies on a small energy gap between the emissive singlet and the non-emissive triplet state, obtained by reducing the wavefunction overlap between donor and acceptor moieties. Efficient emission, however, requires maintaining a good oscillator strength, which is itself based on sufficient overlap of...

Thermally stable silicone elastomers based on silphenylenes are normally white solids at room temperature due to physical interactions between silphenylene moieties that lead to separated domains. We demonstrate that the Piers–Rubinsztajn reaction can be used to prepare highly branched tri- and tetrasilphenylene monomers from commercial alkoxysilan...

Organic long‐persistent luminescence (OLPL) is one of the most promising methods for long‐lived‐emission applications. However, present room‐temperature OLPL emitters are mainly based on a bimolecular exciplex system which usually needs an expensive small molecule such as 2,8‐bis(diphenyl‐phosphoryl)dibenzo[b,d]thiophene (PPT) as the acceptor. In t...

We report two donor-acceptor (D-A) materials based on a cyanoanthracene acceptor paired with diphenylamine (DPAAnCN) and carbazole (CzAnCN) donor moieties. These compounds show hybrid locally excited (LE) charge-transfer (CT) excited states (HLCT), which we demonstrated through a combined photophysical and computational study. Vacuum-deposited orga...

Most traditional methods for silicone elastomer preparation involve catalysts whose incomplete removal can result in compromised thermal stability of the product elastomers and/or safety concerns. Herein, we report the oxidative curing of hydrosilane (H-Si) functionalized polymers to generate silicone elastomers at 250 oC in air but in the absence...

We designed and synthesized two new ambipolar host materials, namely CzPO and Cz3PO. Combining CzPO and Cz3PO with CzTRZ2 as the emitter resulted in improved maximum external quantum efficiencies of 13.1% and 13.2%, respectively, together with small efficiency roll-offs, while the device based on bis[2-(diphenylphosphino)phenyl]ether oxide (DPEPO)...

This chapter discusses the development of purely organic (i.e. metal‐free) small molecule organic solution‐processed thermally activated delayed fluorescence (TADF) materials and their use in organic light‐emitting diode (OLED) devices and compare their performance with the state‐of‐the‐art vacuum‐deposited TADF materials and devices. The developme...

A series of four novel deep blue to sky blue thermally activated delayed fluorescence (TADF) emitters (2CzdOXDMe, 2CzdOXD4MeOPh, 2CzdOXDPh and 2CzdOXD4CF3Ph) have been synthesized and characterized. These oxadiazole-based emitters demonstrated bluer emission compared with reference emitter 2CzPN thanks to the weaker acceptor strength of oxadiazole...

The development of materials for deep blue OLEDs will be presented. A novel donor‐acceptor TADF compound comprising oxadiazole acceptor units was studied. The emission is tuned towards deep‐blue by tuning the acceptor strength, and TADF is demonstrated. Finally, the results are compared with model sky‐blue emitter 2CzPN.

Thermally activated delayed fluorescence (TADF) represents a very promising singlet harvesting mechanism that permits harvesting of both singlet and triplet excitons in electroluminescent devices. In this chapter, the operating principle of TADF mechanism is introduced. Two major classes of TADF emitters employed in light-emitting electrochemical c...

Polymer organic light-emitting diode (PLED) is one of the most studied subjects in flexible electronics thanks to their economical wet fabrication procedure for enhanced price advantage of the product device. In order to optimize PLED efficiency, correlating the polymer structure with the device performance is essential. An important question for t...

Org. thermally activated delayed fluorescence (TADF) species according to Formula I are described. The species have donor (D) and acceptor (A) moieties bonded to a ring system (Q) . Q is an unsatd. carbocyclic or heterocyclic ring system including at least two rings fused together. The ring system Q may include at least one polyunsatd. ring, typica...

A series of five novel sky-blue to green emitting push-pull fluorophores based on phenothiazine donor and 1,3,4- oxadiazole acceptor were synthesized and characterized. Their doped thin films (5 wt% in PMMA) showed high quantum efficiencies (ФPL) from 0.63 to 0.77. These fluorophores also underwent remarkably reversible oxidations and reductions su...

Thermally activated delayed fluorescence (TADF) represents a very promising singlet harvesting mechanism that permits harvesting of both singlet and triplet excitons in electroluminescent devices. In this chapter, the operating principle of TADF mechanism is introduced. Two major classes of TADF emitters employed in light-emitting electrochemical c...

Two deep blue thermally activated delayed fluorescence (TADF) emitters (imCzDPS and imDPADPS) that contain charged imidazolium groups tethered to the central luminophore were designed and synthesized as small molecule organic emitters for light-emitting electrochemical cell (LEEC) electroluminescent devices. The emission profile in doped thin films...

We herein report the first cross comparison of 14 poly(dibenzofulvene) derivatives (13 novel examples and the parent poly(dibenzofulvene)) in order to understand how the choice of substituent affects the physical properties of this interesting class of semiconducting polymers. Electron withdrawing substituents decreased the polymerization reactivit...

The design of Thermally Activated Delayed Fluorescence (TADF) materials both as emitters and as hosts is an exploding area of research. The replacement of phosphorescent metal complexes with inexpensive organic compounds in electroluminescent (EL) devices that demonstrate comparable performance metrics is paradigm shifting as these new materials of...

Thermally Activated Delayed Fluorescence (TADF) compds. wherein two arom. heterocyclic moieties are provided as acceptor groups, spaced apart from two donor moieties by an arom. spacer ring, are described. Charged org. TADF species having a similar structure are also described. The TADF compds. and charged org. TADF species may be employed as emitt...

Charged org. thermally activated delayed fluorescence (TADF) species are described. A light- emitting electrochem. cell (LEEC) includes the charged org. thermally activated delayed fluorescence (TADF) species and sufficient counter ions to balance the charge on the charged org. thermally activated delayed fluorescence species, as emitter material....

Light-emitting electrochemical cells (LECs) based on fluorescent host-guest small molecules system are reported. The LECs show electroluminescence coming solely from the guest, with an external quantum efficiency (EQE) of 2.0%, which is very close to the theoretical maximum EQE (2.2%) for this particular system. This work demonstrates the possibili...

Two novel charged organic thermally activated delayed fluorescence (TADF) emitters, 1 and 2, have been synthesized. Their TADF behavior is well-supported by the multiexponential decay of their emission (nanosecond and microsecond components) and the oxygen dependence of the photoluminescence quantum yields. Spin-coated electroluminescent devices ha...

Five cationic platinum(II) complexes bearing a 2-(3′-substituted aryl)pyridine cyclometalating ligand (C∧N) and a neutral Ar-BIAN ligand have been synthesized: [Pt(ppy)(PhBIAN)]PF6 (1), [Pt(3Fppy)(PhBIAN)]PF6 (2), [Pt(3MeOppy)(PhBIAN)]PF6 (3), [Pt(3MeOppy)(4-FPhBIAN)]PF6 (4), [Pt(ppy)(4-MeOPhBIAN)]PF6 (5). All complexes have been characterized by N...

In this study, a series of four formyl-substituted chloro-bridged iridium(III) dimers were prepared. Their absorption, photophysical and electrochemical properties were studied in dichloromethane solution. It was found that as the formyl content increased on the cyclometalating ligands, emission unexpectedly became brighter. Organic light-emitting...

Two fluorescent monomers N-phenyl-N-(4-vinylphenyl)pyren-1-amine (Vinyl-PyPA) and 1-vinyl pyrene (VPy) were synthesized in good yields. A series of soluble conductive vinyl copolymers P(PyPA-co-VPy) containing Vinyl-PyPA and VPy moieties at different composition ratios were prepared by free radical solution polymerization. These copolymers showed h...

Several series of bipolar small molecules have been synthesized and studied as charge balancing materials for homojunction OLED applications.(1-3) The bipolar molecules consisted of several components including a hole transporting arylamine moiety, an electron transporting oxadiazole moiety and an emitting polycyclic aromatic moiety. The achievemen...

A series of novel substituted (2-methoxy, 2-nitro, 2-bromo, 2-iodo, 2-cyano, and 2-acetyl) and disubstitiuted (2-bromo-7-methoxy, 2-bromo-7-propoxy, 2-bromo-7-hexoxy, 2-nitro-7-propoxy, 2-nitro-7-hexoxy, and 2,7-di-bromo) dibenzofulvenes have been prepared from the corresponding fluorenes with fair to very good overall yields (35.7–66.7%) based on...

In a homojunction device, a single organic layer assumes the multiple roles of hole, electron transportation, and emitter. Its ease in processing is highly desirable from the manufacturing point of view. In this paper, we shall describe the synthesis of a range of bipolar small molecules and conductive vinyl polymers for application in homojunction...