Substituted benzo[4,5]imidazo[1,2-F]phenanthridines, dibenzo[I.K]benzo[4,5]imidazo[1,2-F]benzofurophenanthridines and dibenzo[I.K]benzo[4,5]imidazo[1,2-F]benzo[4,5]thienophenanthridines as thermally assisted delayed fluorescent materials
Inventors
Assignees
Publication Number
US-10851106-B2
Publication Date
2020-12-01
Expiration Date
2038-05-18
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Abstract
Thermally assisted delayed fluorescent materials with triad-type materials for use in full color displays and lighting applications with the following generic structures are provided:
Core Innovation
The invention provides thermally assisted delayed fluorescent (TADF) materials characterized by triad-type molecules, specifically including cyclic donor-donor'-acceptor (D-D'-A) and donor-acceptor-acceptor' (D-A-A') structures as described by general formulas in the patent. These materials are designed for use in light emitting complexes and devices, with their structural features enabling significant reduction of the singlet excited state energy by conjugation, while the lowest triplet state remains localized, resulting in a small singlet-triplet energy splitting. These molecules can incorporate a variety of donor and acceptor groups, which are extensively defined in the specification.
The problem addressed by the invention is the reliance of most existing TADF materials on donor-acceptor concepts using strong donor and acceptor groups that induce large molecular geometry distortions to achieve a small energy gap between singlet and triplet excited states (S1–T1). Such designs typically utilize acceptor groups with poor electrochemical stability, which decreases device operational stability in practical applications, such as organic light emitting diodes (OLEDs).
The disclosed TADF materials overcome this limitation by allowing the use of weaker donors or acceptors and by providing conjugated triad-type core structures that maintain the optical and electronic properties necessary for device stability and efficiency. The compounds can serve as robust emitters or host materials for OLED applications, facilitating improved design flexibility and operational stability for display and lighting technologies.
Claims Coverage
There are two primary independent inventive features claimed: novel compounds of specific triad-type TADF molecular structures and their direct incorporation into light emitting diodes and devices.
Triad-type TADF molecule compound
A compound represented by a specific formula as disclosed in the claims and description, where the molecule is a substituted benzo[4,5]imidazo[1,2-F]phenanthridine, dibenzo[I.K]benzo[4,5]imidazo[1,2-F]benzofurophenanthridine, or dibenzo[I.K]benzo[4,5]imidazo[1,2-F]benzo[4,5]thienophenanthridine structure. The formula includes explicit definitions for donor and acceptor substituents as detailed in the specification.
Light emitting diode including the triad-type TADF compound
A light emitting diode that comprises at least one compound as described by the triad-type formula in claim 1, functioning as an emitter or within the device structure.
Light emitting device including the light emitting diode
A light emitting device comprising the light emitting diode containing the compound of the invention, enabling the realization of devices such as those for display and lighting.
Alternative triad-type TADF molecule compound
A compound represented by a second specific formula as disclosed, where the structure includes the differentiated donor and acceptor patterns defined in the claims, with the same full scope of donor and acceptor groups as set forth in the description.
Light emitting diode including the alternative triad-type TADF compound
A light emitting diode that comprises at least one compound defined by the formula in claim 5 as an emissive component.
Light emitting device including the alternative diode
A light emitting device comprising the light emitting diode that uses the alternative claimed compound.
The claims broadly cover two major sets of novel TADF compounds with detailed structure definitions and specify their application in light emitting diodes and devices, thus protecting both the molecules and their functional incorporation into optoelectronic products.
Stated Advantages
The disclosed design allows incorporation of weak donors or acceptors, making TADF material more feasible as stable emitters or host materials for OLED applications.
Triad-type TADF structures reduce singlet-triplet energy splitting, facilitating efficient emission without requiring large geometric distortion of the molecule.
The design avoids using acceptor-type groups with inferior electrochemical stability, resulting in improved device operational stability.
Documented Applications
Use in organic light emitting diodes (OLEDs) for full color displays.
Use in lighting applications, specifically as emissive materials or hosts in light emitting devices.
Use in light emitting devices and luminescent display devices as described in the patent.
Use in photovoltaic devices comprising the disclosed TADF complexes or compositions.
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