Red/Near‐Infrared Thermally Activated Delayed Fluorescence OLEDs with Near 100 % Internal Quantum Efficiency

Developing red thermally activated delayed fluorescence (TADF) emitters, attainable for both high‐efficient red organic light‐emitting diodes (OLEDs) and non‐doped deep red/near‐infrared (NIR) OLEDs, is challenging. Now, two red emitters, BPPZ‐PXZ and mDPBPZ‐PXZ, with twisted donor–acceptor structures were designed and synthesized to study molecular design strategies of high‐efficiency red TADF emitters. BPPZ‐PXZ employs the strictest molecular restrictions to suppress energy loss and realizes red emission with a photoluminescence quantum yield (Φ_PL) of 100±0.8 % and external quantum efficiency (EQE) of 25.2 % in a doped OLED. Its non‐doped OLED has an EQE of 2.5 % owing to unavoidable intermolecular π–π interactions. mDPBPZ‐PXZ releases two pyridine substituents from its fused acceptor moiety. Although mDPBPZ‐PXZ realizes a lower EQE of 21.7 % in the doped OLED, its non‐doped device shows a superior EQE of 5.2 % with a deep red/NIR emission at peak of 680 nm.     

Deep‐Red to Near‐Infrared Thermally Activated Delayed Fluorescence in Organic Solid Films and Electroluminescent Devices

The design and synthesis of highly efficient deep red (DR) and near‐infrared (NIR) organic emitting materials with characteristic of thermally activated delayed fluorescence (TADF) still remains a great challenge. A strategy was developed to construct TADF organic solid films with strong DR or NIR emission feature. The triphenylamine (TPA) and quinoxaline‐6,7‐dicarbonitrile (QCN) were employed as electron donor (D) and acceptor (A), respectively, to synthesize a TADF compound, TPA‐QCN. The TPA‐QCN molecule with orange‐red emission in solution was employed as a dopant to prepare DR and NIR luminescent solid thin films. The high doped concentration and neat films exhibited efficient DR and NIR emissions, respectively. The highly efficient DR and NIR organic light‐emitting devices (OLEDs) were fabricated by regulating TPA‐QCN dopant concentration in the emitting layers.     

Twisted penta‐Carbazole/Benzophenone Hybrid Compound as Multifunctional Organic Host,Dopant or Non‐doped Emitter for Highly Efficient Solution‐Processed Delayed Fluorescence OLEDs

A new multi‐functional penta‐carbazole/benzophenone hybrid compound 5CzBP was designed and synthesized through a simple one‐step catalyst‐free C—N coupling reaction by using 2,3,4,5,6‐pentafluorobenzophenone and carbazole as starting materials. 5CzBP is very soluble in tetrahydrofuran (THF), which brings an environmentally friendly device fabrication for solution‐processed OLEDs instead of most widely used chlorinated solvents when 5CzBP is employed as the bulk‐phase of organic host or non‐doped emitter in the emissive layer. 5CzBP exhibits thermally activated delayed fluorescence (TADF) characteristic with relatively high triplet energy of 2.60 eV and a low ΔE_ST of 0.01 eV. By using the new TADF material as organic host for another green TADF emitter, maximum external quantum efficiency (EQE) of 12.5% has been achieved in simple solution‐processed OLED device. Besides, a maximum EQE of 8.9% and 5.7% was further obtained in TADF devices based on 5CzBP as dopant and non‐doped emitter, respectively. The simultaneously acting as efficient TADF host and non‐doped TADF emitter provides the potential guidance of the future simple single‐layer two‐color white OLEDs based on low‐cost pure organic TADF materials.     

A Simple and Strong Electron‐Deficient 5,6‐Dicyano[2,1,3]benzothiadiazole‐Cored Donor‐Acceptor‐Donor Compound for Efficient Near Infrared Thermally Activated Delayed Fluorescence

Despite the success of thermally activated delayed fluorescent (TADF) materials in steering the next generation of organic light‐emitting diodes (OLEDs), effective near infrared (NIR) TADF emitters are still very rare. Here, we present a simple and extremely high electron‐deficient compound, 5,6‐dicyano[2,1,3]benzothiadiazole (CNBz), as a strong electron‐accepting unit to develop a sufficiently strong donor‐acceptor (D?A) interaction for NIR emission. End‐capping with the electron‐donating triphenylamine (TPA) unit created an effective D?A?D type system, giving rise to an efficient NIR TADF emissive molecule (λ_em=750 nm) with a very small ΔE_ST of 0.06 eV. The electroluminescent device using this NIR TADF emitter exhibited an excellent performance with a high maximum radiance of 10020 mW Sr^?1 m^?2, a maximum EQE of 6.57% and a peak wavelength of 712 nm.     

Dibenzo[a,j]phenazine‐Cored Donor–Acceptor–Donor Compounds as Green‐to‐Red/NIR Thermally Activated Delayed Fluorescence Organic Light Emitters

A new family of thermally activated delayed fluorescence (TADF) emitters based on U‐shaped D‐A‐D architecture with a novel accepting unit has been developed. All investigated compounds have small singlet‐triplet energy splitting (ΔE_ST) ranging from 0.02 to 0.20 eV and showed efficient TADF properties. The lowest triplet state of the acceptor unit plays the key role in the TADF mechanism. OLEDs fabricated with these TADF emitters achieved excellent efficiencies up to 16 % external quantum efficiency (EQE).     

Intermolecular Charge‐Transfer Transition Emitter Showing Thermally Activated Delayed Fluorescence for Efficient Non‐Doped OLEDs

A novel molecular model of connecting electron‐donating (D) and electron‐withdrawing (A) moieties via a space‐enough and conjugation‐forbidden linkage (D‐Spacer‐A) is proposed to develop efficient non‐doped thermally activated delayed fluorescence (TADF) emitters. 10‐(4‐(4‐(4,6‐diphenyl‐1,3,5‐triazin‐2‐yl) phenoxy) phenyl)‐9,9‐dimethyl‐9,10‐dihydroacridine (DMAC‐o‐TRZ) was designed and synthesized accordingly. As expected, it exhibits local excited properties in single‐molecule state as D‐Spacer‐A molecular backbone strongly suppress the intramolecular charge‐transfer (CT) transition. And intermolecular CT transition acted as the vital radiation channel for neat DMAC‐o‐TRZ film. As in return, the non‐doped device exhibits a remarkable maximum external quantum efficiency (EQE) of 14.7 %. These results prove the feasibility of D‐Spacer‐A molecules to develop intermolecular CT transition TADF emitters for efficient non‐doped OLEDs.     

Meta Junction Promoting Efficient Thermally Activated Delayed Fluorescence in Donor‐Acceptor Conjugated Polymers

The meta junction is proposed to realize efficient thermally activated delayed fluorescence (TADF) in donor–acceptor (D‐A) conjugated polymers. Based on triphenylamine as D and dicyanobenzene as A, as a proof of concept, a series of D‐A conjugated polymers has been developed by changing their connection sites. When the junction between D and A is tuned from para to meta, the singlet–triplet energy splitting (ΔE_ST) is found to be significantly decreased from 0.44 to 0.10 eV because of the increasing hole–electron separation. Unlike the para‐linked analogue with no TADF, consequently, the meta‐linked polymer shows a strong delayed fluorescence. Its corresponding solution‐processed organic light‐emitting diodes (OLEDs) achieve a promising external quantum efficiency (EQE) of 15.4 % (51.9 cd A^?1, 50.9 lm W^?1) and CIE coordinates of (0.34, 0.57). The results highlight the bright future of D‐A conjugated polymers used for TADF OLEDs.     

Efficient Nondoped Pure Blue Organic Light‐Emitting Diodes Based on an Anthracene and 9,9‐Diphenyl‐9,10‐dihydroacridine Derivative

Organic light‐emitting diodes (OLEDs) have been greatly developed in recent years owing to their abundant advantages for full‐color displays and general‐purpose lightings. Blue emitters not only provide one of the primary colors of the RGB (red, green and blue) display system to reduce the power consumption of OLEDs, but are able able to generate light of all colors, including blue, green, red, and white by energy transfer processes in devices. However, it remains a challenge to achieve high‐performance blue electroluminescence, especially for nondoped devices. In this paper, we report a blue light emitting molecule, DPAC‐AnPCN, which consists of 9,9‐diphenyl‐9,10‐dihydroacridine and p‐benzonitrile substituted anthracene moieties. The asymmetrically decoration on anthracene with different groups on its 9 and 10 positions combines the merits of the respective constructing units and endows DPAC‐AnPCN with pure blue emission, high solid‐state efficiency, good thermal stability and appropriate HOMO and LUMO energy levels. Furthermore, DPAC‐AnPCN can be applied in a nondoped device to effectively reduce the fabrication complexity and cost. The nondoped device exhibits pure blue electroluminescence (EL) locating at 464 nm with CIE coordinates of (0.15, 0.15). Moreover, it maintains high efficiency at relatively high luminescence. The maximum external quantum efficiency (EQE) reaches 6.04 % and still remains 5.31 % at the luminance of 1000 cd m^?2 showing a very small efficiency roll‐off.     

Phosphorescent Cyclometalated Iridium(III) Complexes That Contain Substituted 2‐Acetylbenzo[b]thiophen‐3‐olate Ligand for Red Organic Light‐Emitting Devices

We report the synthesis of a new class of thermally stable and strongly luminescent cyclometalated iridium(III) complexes 1 – 6 , which contain the 2‐acetylbenzo[b]thiophene‐3‐olate (bt) ligand, and their application in organic light‐emitting diodes (OLEDs). These heteroleptic iridium(III) complexes with bt as the ancillary ligand have a decomposition temperature that is 10–20 % higher and lower emission self‐quenching constants than those of their corresponding complexes with acetylacetonate (acac). The luminescent color of these iridium(III) complexes could be fine‐tuned from orange (e.g., 2‐phenyl‐6‐(trifluoromethyl)benzo[d]thiazole (cf₃bta) for 4 ) to pure red (e.g., lpt (Hlpt=4‐methyl‐2‐(thiophen‐2‐yl)quinolone) for 6 ) by varying the cyclometalating ligands (C‐deprotonated C^N). In particular, highly efficient OLEDs based on 6 as dopant (emitter) and 1,3‐bis(carbazol‐9‐yl)benzene (mCP) as host that exhibit stable red emission over a wide range of brightness with CIE chromaticity coordinates of (0.67, 0.33) well matched to the National Television System Committee (NTSC) standard have been fabricated along with an external quantum efficiency (EQE) and current efficiency of 9 % and 10 cd A^?1, respectively. A further 50 % increase in EQE (>13 %) by replacing mCP with bis[4‐(6H‐indolo[2,3‐b]quinoxalin‐6‐yl)phenyl]diphenylsilane (BIQS) as host for 6 in the red OLED is demonstrated. The performance of OLEDs fabricated with 6 (i.e., [(lpt)₂Ir(bt)]) was comparable to that of the analogous iridium(III) complex that bore acac (i.e., [(lpt)₂Ir(acac)]; 6 a in this work) [Adv. Mater.­ 2011 , 23, 2981] fabricated under similar conditions. By using ntt (Hnnt=3‐hydroxynaphtho[2,3‐b]thiophen‐2‐yl)(thiophen‐2‐yl)methanone) ligand, a substituted derivative of bt, the [(cf₃bta)₂Ir(ntt)] was prepared and found to display deep red emission at around 700 nm with a quantum yield of 12 % in mCP thin film.     

Achieving Pure Deep‐Blue Electroluminescence with CIE y≤0.06 via a Rational Design Approach for Highly Efficient Non‐Doped Solution‐Processed Organic Light‐Emitting Diodes

Deep‐blue fluorescent emitters with Commission Internationale de l'Eclairage (CIE) y≤0.06 are urgently needed for high‐density storage, full‐color displays and solid‐state lighting. However, developing such emitters with high color purity and efficiency in solution‐processable non‐doped organic light‐emitting diodes (OLEDs) remains an important challenge. Here, we present the synthesis of two new deep‐blue fluorescent emitters ( AFpTPI and AFmTPI ) based on 10‐(9,9‐diethyl‐9H‐fluoren‐2‐yl)‐9,9‐dimethyl‐9,10‐dihydroacridine as a core and 1,3‐ and/or 1,4‐phenylene‐linked triphenylimidazole (TPI) analogues for non‐doped solution‐processable OLEDs. Their thermal, photophysical, electrochemical, and device characteristics are explored, and also strongly supported by density functional theory (DFT) study. AFpTPI and AFmTPI exhibit excellent thermal stability (≈450 °C) with high glass transition temperatures (T_g; 141–152 °C) and deep‐blue emission with high quantum yields. Specifically, the solution‐processed non‐doped device with AFpTPI as an emitter exhibits a maximum external quantum efficiency (EQE) of 4.56 % with CIE coordinates of (0.15, 0.06), which exactly matches the European Broadcasting Union (EBU) blue standard. In addition, AFmTPI also displays good efficiency and better color purity (EQE: 3.37 %; CIE (0.15, 0.05)). To the best of our knowledge, the present work is the first report on non‐doped solution‐processable OLEDs with efficiency close to 5 % and CIE y≤0.06.     

Highly Efficient Near‐Infrared Organic Light‐Emitting Diode Based on a Butterfly‐Shaped Donor–Acceptor Chromophore with Strong Solid‐State Fluorescence and a Large Proportion of Radiative Excitons

The development of near‐infrared (NIR) organic light‐emitting diodes (OLEDs) is of growing interest. Donor–acceptor (D–A) chromophores have served as an important class of NIR materials for NIR OLED applications. However, the external quantum efficiencies (EQEs) of NIR OLEDs based on conventional D–A chromophores are typically below 1 %. Reported herein is a butterfly‐shaped D–A compound, PTZ‐BZP. A PTZ‐BZP film displayed strong NIR fluorescence with an emission peak at 700 nm, and the corresponding quantum efficiency reached 16 %. Remarkably, the EQE of the NIR OLED based on PTZ‐BZP was 1.54 %, and a low efficiency roll‐off was observed, as well as a high radiative exciton ratio of 48 %, which breaks through the limit of 25 % in conventional fluorescent OLEDs. Experimental and theoretical investigations were carried out to understand the excited‐state properties of PTZ‐BZP.     

Molecular Design Strategy for Orange Red Thermally Activated Delayed Fluorescence Emitters in Organic Light-Emitting Diodes (OLEDs)

Pure organic molecules based thermally activated delayed fluorescence (TADF) emitters have been successfully developed in recent years for their propitious application in highly efficient organic light emitting diodes (OLEDs). In the case of orange red emitters, the non-radiative process is known to be a serious issue due to its lower lying singlet energy level. However, recent studies indicate that there are tremendous efforts put to develop efficient orange red TADF emitters. In addition, the external quantum efficiency (EQE) of heteroaromatic based orange red TADF OLEDs surpassed 30 %. Such heteroaromatic type emitters showed wide emission spectra; therefore, more attention is being paid to develop highly efficient orange red TADF emitters along with good color purity. Herein, the recent progress of orange red TADF emitters based on molecular structures, such as cyanobenzene, heteroaromatic, naphthalimide, and boron-based acceptors, are reviewed. Further, our insight on these acceptors has been provided by their photophysical studies and device performances. Future perspectives of orange red TADF emitters for real practical applications are discussed.     

Rigid Bridge-Confined Double-Decker Platinum(II) Complexes Towards High-Performance Red and Near-Infrared Electroluminescence

A molecular design to high-performance red and near-infrared (NIR) organic light-emitting diodes (OLEDs) emitters remains demanding. Herein a series of dinuclear platinum(II) complexes featuring strong intramolecular Pt???Pt and π–π interactions has been developed by using N-deprotonated α-carboline as a bridging ligand. The complexes in doped thin films exhibit efficient red to NIR emission from short-lived (τ=0.9–2.1 μs) triplet metal-metal-to-ligand charge transfer (³MMLCT) excited states. Red OLEDs demonstrate high maximum external quantum efficiencies (EQEs) of up to 23.3 % among the best Pt^II-complex-doped devices. The maximum EQE of 15.0 % and radiance of 285 W sr^?1 m^?2 for NIR OLEDs (λ_EL=725 nm) are unprecedented for devices based on discrete molecular emitters. Both red and NIR devices show very small efficiency roll-off at high brightness. Appealing operational lifetimes have also been revealed for the devices. This work sheds light on the potential of intramolecular metallophilicity for long-wavelength molecular emitters and electroluminescence.     

Molecular Design Strategy of Thermally Activated Delayed Fluorescent Emitters Using CN‐Substituted Imidazopyrazine as a New Electron‐Accepting Unit

Thermally activated delayed fluorescence (TADF)‐based organic light‐emitting diodes (OLEDs) have attracted enormous attention recently due to their capability to replace conventional phosphorescent organic light‐emitting diodes for practical applications. In this work, a newly designed CN‐substituted imidazopyrazine moiety was utilized as an electron‐accepting unit in a TADF emitter. Two TADF emitters, 8‐(3‐cyano‐4‐(9,9‐dimethylacridin‐10(9H)‐yl)phenyl)‐2‐phenylimidazo[1,2‐a]pyrazine‐3‐carbonitrile (Ac‐CNImPyr) and 8‐(3‐cyano‐4‐(10H‐phenoxazin‐10‐yl)phenyl)‐2‐phenylimidazo[1,2‐a]pyrazine‐3‐carbonitrile (PXZ‐CNImPyr), were developed based on the CN‐substituted imidazopyrazine acceptor combined with acridine and phenoxazine donor, respectively. A CN‐substituted phenyl spacer was introduced between the donor and acceptor for a sufficiently small singlet‐triplet energy gap (ΔE_ST) and molecular orbital management. Small ΔE_ST of 0.07 eV was achieved for the phenoxazine donor‐based PXZ‐CNImPyr emitter. As a result, an organic light‐emitting diode based on the PXZ‐CNImPyr emitter exhibited a high external quantum efficiency of up to 12.7 %, which surpassed the EQE limit of common fluorescent emitters. Hence, the CN‐modified imidazopyrazine unit can be introduced as a new acceptor for further modifications to develop efficient TADF‐based OLEDs.     

Adamantane‐Substituted Acridine Donor for Blue Dual Fluorescence and Efficient Organic Light‐Emitting Diodes

To date, blue dual fluorescence emission (DFE) has not been realized because of the limited choice of chemical moieties and severe geometric deformation of the DFE emitters leading to strong intramolecular charge transfer (ICT) with a large Stokes shift in excited states. Herein, an emitter (1′r,5′R,7′S)‐10‐(4‐(4,6‐diphenyl‐1,3,5‐triazin‐2‐yl)phenyl)‐10H‐spiro [acridine‐9,2′‐adamantane] (a‐DMAc‐TRZ) containing a novel adamantane‐substituted acridine donor is reported, which exhibits unusual blue DFE. The introduction of the rigid and bulky adamantane moiety not only suppressed the geometry relaxation in excited state, but also induced the formation of quasi‐axial conformer (QAC) and quasi‐equatorial conformer (QEC) geometries, leading to deep‐blue conventional fluorescence and sky‐blue thermally activated delayed fluorescence (TADF). The resulting organic light‐emitting diodes (OLEDs) achieved a maximum external quantum efficiency (EQE) of about 29 %, which is the highest reported for OLEDs based on dual‐conformation emitters.     

Deep‐red light‐emitting phosphorescent dendrimer encapsulated tris‐[2‐benzo[b]thiophen‐2‐yl‐pyridyl] iridium (III) core for light‐emitting device applications

New deep‐red light‐emitting phosphorescent dendrimers with hole‐transporting carbazole dendrons were synthesized by reacting tris(2‐benzo[b]thiophen‐2‐yl‐pyridyl) iridium (III) complex with carbazolyl dendrons by DCC‐catalyzed esterification. The resulting first‐, second‐, and third‐generation dendrimers were found to be highly efficient as solution‐processable emitting materials and for use in host‐free electrophosphorescent light‐emitting diodes. We fabricated a host‐free dendrimer EL device with configuration ITO/PEDOT:PSS (40 nm)/dendrimer (55 nm)/BCP (10 nm)/Alq₃ (40 nm)/LiF (1 nm)/Al (100 nm) and characterized the device performance. The multilayered devices showed luminance of 561 cd/m² at 383.4 mA/cm² (12 V) for 15 , 1302 cd/m² at 321.3 mA/cm² (14 V) for 16 , and 422 cd/m² at 94.4 mA/cm² (18 V) for 17 . The third‐generation dendrimer, 17 (η_ext = 6.12% at 7.5 V), showed the highest external quantum efficiency (EQE) with an increase in the density of the light‐harvesting carbazole dendron. Three dendrimers exhibited considerably pure deep‐red emission with CIE 1931 (Commission International de L'Eclairage) chromaticity coordinates of x = 0.70, y = 0.30. The CIE coordinates remained very stable with the current density. The integration of rigid hole‐transporting dendrons and phosphorescent complexes provides a new route to design highly efficient solution‐processable materials for dendrimer light‐emitting diode (DLED) applications. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7517–7533, 2008     

Highly near‐infrared emissive boron di(iso)indomethene‐based polymer: Drastic change from deep‐red to near‐infrared emission via quantitative polymer reaction

It is challenging to realize the near‐infrared (NIR) emission with large brightness and sharp spectra from the conjugated polymers. In this study, we demonstrate the strategy for receiving strong and pure NIR emission from polymeric materials using organoboron complexes and the modification after polymerization. A series of NIR emissive conjugated polymers with boron di(iso)indomethenes (BODINs) and fluorene or bithiophene were synthesized by Suzuki–Miyaura coupling reaction. The obtained polymers exhibited high emissions in the range from deep‐red to NIR region (quantum yields: ?_PL = 0.40–0.79, full width at half maximum height: Δλ_1/2 = 660–940 cm^?1, emission maxima: λ_PL = 686–714 nm). Next, the demethylation of the BODIN‐based polymer with o‐methoxyphenyl groups was carried out. The transformation of the polymer structure quantitatively proceeded via efficient intramolecular crosslinking through the intermediary of the boron atom. Finally, the resulting polymer showed both drastically larger red‐shifted and sharper photoluminescence spectrum than that of the parent polymer with deep‐red emission (?_PL = 0.37, Δλ_1/2 = 460 cm^?1, λ_PL = 758 nm). © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Synthesis and electroluminescent performance of thermally activated delayed fluorescence‐conjugated polymers with simple formylphenyl as pendant acceptor

Formylphenyl has been demonstrated to act as an acceptor to construct thermally activated delayed fluorescence (TADF) emitter, and therefore a series of the TADF‐conjugated polymers with formylphenyl as pendant acceptor and carbazole/acridine as backbone donor are designed and synthesized. All polymers involve the twisted donor/acceptor structural moieties with the sufficiently spatial separation between the highest occupied molecular orbital and the lowest unoccupied molecular orbital as well as a small singlet/triplet splitting, and exhibit the legible TADF features confirmed by theoretical calculation and their transient decay spectra. The solution‐processed organic light‐emitting diodes using neat film of the polymers as emissive layer achieve excellent performance with the maximum external quantum efficiency (EQE) of up to 10.6%, the maximum current efficiency of up to 35.3 cd A⁻¹ and the low turn‐on voltage of 2.7 V. Moreover, the EQE still remains 10.3% at the luminance of 1000 cd m⁻² with the low driving voltage of 4.4 V and extremely small efficiency roll‐off. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 1989–1996     

Controlling Singlet–Triplet Energy Splitting for Deep‐Blue Thermally Activated Delayed Fluorescence Emitters

The development of efficient metal‐free organic emitters with thermally activated delayed fluorescence (TADF) properties for deep‐blue emission is still challenging. A new family of deep‐blue TADF emitters based on a donor–acceptor architecture has been developed. The electronic interaction between donor and acceptor plays a key role in the TADF mechanism. Deep‐blue OLEDs fabricated with these TADF emitters achieved high external quantum efficiencies over 19.2 % with CIE coordinates of (0.148, 0.098).     

Organic Crystals with Near‐Infrared Amplified Spontaneous Emissions Based on 2′‐Hydroxychalcone Derivatives: Subtle Structure Modification but Great Property Change

A series of highly efficient deep red to near‐infrared (NIR) emissive organic crystals 1 – 3 based on the structurally simple 2′‐hydroxychalcone derivatives were synthesized through a simple one‐step condensation reaction. Crystal 1 displays the highest quantum yield (Φ_f) of 0.32 among the reported organic single crystals with an emission maximum (λ_em) over 710 nm. Comparison between the bright emissive crystals 1 – 3 and the nearly nonluminous compounds 4 – 7 clearly gives evidence that a subtle structure modification can arouse great property changes, which is instructive in designing new high‐efficiency organic luminescent materials. Notably, crystals 1 – 3 exhibit amplified spontaneous emissions (ASE) with extremely low thresholds. Thus, organic deep red to NIR emissive crystals with very high Φ_f have been obtained and are found to display the first example of NIR fluorescent crystal ASE.