All-fluorescence white organic light-emitting diodes with record-beating power efficiencies over 130 lm W‒1 and small roll-offs

Triarylboron-Based Dual Thermally Activated Delayed Fluorescence Emitter for Single Molecule White Light-Emitting Diodes

Single-molecule emitters with dual thermally activated delayed fluorescence (TADF) characteristics are very promising for application in organic light-emitting diodes (OLEDs). Rarely reported, organic dual-TADF materials, especially mechanochromic materials, are in demand. We present two donor-acceptor emitters, Mes*BA-Ac and FXylBA-Ac, which exhibit dual-TADF in the solid state due to the separation of HOMO and LUMO and strong intermolecular interactions. Their phase transition from amorphous to crystalline under stimuli leads to switchable TADF emissions. By blending Mes*BA-Ac with poly(methyl methacrylate), we achieve pure white light with Commission Internationale de l'Eclairage (CIE) coordinates of (0.33, 0.32). Furthermore, single-molecule white organic light-emitting diodes (SM-WOLEDs) using Mes*BA-Ac have been fabricated, reaching a maximum external quantum efficiency (EQEmax) of 1.65% with CIE coordinates of (0.30, 0.31). More importantly, the dual-TADF emission mechanism enables the devices to maintain stable white-light emission across a relatively wide voltage range, providing valuable insights for the advancement of pure organic SM-WOLEDs.

1,4-Azaborine Participation Enables Inaccessible Cycloarene with Unique Photophysical Properties

Cycloarenes and heterocycloarenes, characterized by fused macrocyclic π-conjugated structures, hold significant promise in synthetic chemistry and materials science. However, their further development remains constrained by formidable synthetic challenges, particularly for those with contracted cavities. Inspired by advances in the synthesis of organoboron-based multiresonance thermally activated delayed fluorescence (TADF) emitters, we herein report the convenient access and detailed characterization of a 1,4-azaborine-embedded cycloarene that features the smallest cavity among known (hetero)cycloarenes. The contracted cavity induces a bowl-shaped molecular geometry, as confirmed by crystallographic analysis, while also triggering through-space conjugation with delocalized π-electrons at the cavity site. Comparative studies between this compound and its helical analogue reveal a substantial topological impact on photophysical properties, including a bathochromic-shifted and broadened emission band, prolonged radiative decay process, and more efficient triplet-to-singlet spin-flip. Capitalizing on its efficient TADF with a remarkably high quantum yield, we successfully fabricated the first (hetero)cycloarene-based organic light-emitting diodes, achieving over 30% external quantum efficiency and minimal efficiency roll-off. These findings offer new insights into the design of topologically distinct organic compounds with unique properties.

Aggregation suppression and enhanced blue emission of perylene in zinc-based coordination polymer glass

Reducing aggregation caused quenching and enhancing stability is crucial in the fabrication of organic light-emitting diodes. Herein, we successfully fabricated blue-emitting coordination polymer glasses using perylene dye and a zinc-based coordination glass. The aggregation of perylene monomers in the solid state was significantly suppressed, and the hybrid glass demonstrated high stability and strong photoluminescent quantum yield (75.5%) under ambient conditions.

High-power-efficiency and ultra-long-lifetime white OLEDs empowered by robust blue multi-resonance TADF emitters

White organic light-emitting diodes (WOLEDs) show very promising as next-generation light-sources, but achieving high power efficiency (PE) and long operational lifetime remains challenging because of the lack of stable blue emitters that can harvest all triplet (T1) excitons for light emission. Herein, we propose integrating stable azure multi-resonance thermally activated delayed fluorescent (MR-TADF) emitters into tri-color hybrid WOLEDs to tackle these issues. By meticulously selecting MR-TADF emitters and precisely tuning the exciton recombination zone, the optimized tri-color devices based on BCzBN-3B achieve color-stable white light emission with maximum external quantum efficiency (EQEmax) and maximum PE (PEmax) of 34.4% and 101.8 lm W-1, respectively. Furthermore, the LT90, defined as the time for the luminance to drop to 90% of its initial value at 1000 cd m-2, reaches 761 h. In addition, a hybrid WOLED with deep blue emitter developed using our strategy achieves a high color rendering index of 88 and an EQEmax of 30.6%, further demonstrating the versatility and effectiveness of our approach. The record-breaking efficiency and ultra-long lifetime underscore the success of hybrid white-light devices by incorporating robust blue MR-TADF emitters. These advancements open new avenues for commercialization of hybrid WOLEDs, presenting promising solutions for energy-efficient lighting and display technologies.

A perspective on next-generation hyperfluorescent organic light-emitting diodes

Hyperfluorescence, also known as thermally activated delayed fluorescence (TADF) sensitized fluorescence, is known as a next-generation efficient and innovative process for high-performance organic light-emitting diodes (OLEDs). High external quantum efficiency (EQE) and good color purity are crucial parameters for display applications. Hyperfluorescent OLEDs (HF-OLEDs) take the lead in this respect as they utilize the advantages of both TADF emitters and fluorescent dopants, realizing high EQE with color saturation and long-term stability. Hyperfluorescence is mediated through Förster resonance energy transfer (FRET) from a TADF sensitizer to the final fluorescent emitter. However, competing loss mechanisms such as Dexter energy transfer (DET) of triplet excitons and direct charge trapping on the final emitter need to be mitigated in order to achieve fluorescence emission with high efficiency. Despite tremendous progress, appropriate guidelines and fine optimization are still required to address these loss channels and to improve the device operational lifetime. This perspective aims to provide an overview of the evolution of HF-OLEDs by reviewing both molecular and device design pathways for highly efficient narrowband devices covering all colors of the visible spectrum. Existing challenges and potential solutions, such as molecules with peripheral inert substitution, multi-resonant (MR) TADF emitters as final dopants, and exciplex-sensitized HF-OLEDs, are discussed. Furthermore, the operational device lifetime is reviewed in detail before concluding with suggestions for future device development.

Construction of acenaphthylenes via C-H activation-based tandem penta- and hexaannulation reactions

Acenaphthylene-containing polycyclic aromatic hydrocarbons (AN-PAHs) are noteworthy structural motifs for organic functional materials due to their non-alternant electronic structure, which increases electron affinity. However, the synthesis of AN-PAHs has traditionally required multiple sequential synthetic steps, limiting structural diversity. Herein, we present a tandem C-H penta- and hexaannulation reaction of aryl alkyl ketone with acetylenedicarboxylate. This integrated approach enhances overall efficiency and selectivity, marking a significant advancement in AN-PAH synthesis. Mechanistic studies unveil an orchestrated extension of five- and six-membered rings through C-H activation-annulation and Diels-Alder reaction. Additionally, the tandem annulation reaction can be performed stepwise, further validating the proposed mechanism and increasing the structural diversity of AN-PAHs.

Harmonization of rapid triplet up-conversion and singlet radiation enables efficient and stable white OLEDs

White organic light-emitting diodes (WOLEDs) hold significant promise in illumination and displays, but achieving high efficiency while maintaining stability is an ongoing challenge. Here, we strategically combine a blue donor-acceptor thermally activated delayed fluorescence (TADF) emitter featuring rapid reverse intersystem crossing rate and a yellow multi-resonance TADF emitter renowned for the fast radiative transition process to achieve warm WOLEDs with exceptional power efficiency exceeding 190 lm W-1 and external quantum efficiency (EQE) of 39%, setting records for WOLEDs. Meanwhile, these devices also exhibit an extended operational lifetime (LT80) of 446 h at an initial luminance of 1000 cd m-2. Another group of blue and yellow emitters based on our strategy achieves a standard white emission and a high EQE of 35.6%, confirming the universality of our strategy. This work presents a versatile strategy to harmonize singlet exciton radiation and triplet exciton up-conversion, thus achieving a win-win situation of efficiency and stability.

Molecular Engineering Towards Efficient Aggregation-Induced Delayed Fluorescence Luminogens as Emitters and Sensitizers for High-Performance Organic Light-Emitting Diodes

Exploring efficient thermally-activated delayed fluorescence materials having maximum external quantum efficiencies (ηext,maxs) exceeding 30 % for organic light-emitting diodes (OLEDs) still remains challenging because it generally requires efficient reverse intersystem crossing (RISC), high photoluminescence quantum yield (ΦPL), and large optical out-coupling efficiency (Φout) simultaneously. Herein, two green aggregation-induced delayed fluorescence (AIDF) luminogens, named XTCz-2 and XTCz-3, are designed and constructed by using xanthone (XT) as electron acceptor and phenylcarbazole-substituted carbazole as donors. XTCz-2 and XTCz-3 exhibit distinguished advantages of high thermal stability (439-560 °C), excellent ΦPLs (84-88 %) and fast RISC rates (1.9×105-4.2×105 s-1), and prefer horizontal dipole orientation and thus have high Φouts. Consequently, they can achieve the state-of-the-art electroluminescence (EL) performances with ηext,maxs of up to 35.0 %. Moreover, XTCz-3 is selected as a sensitizer for sky-blue multi-resonance delayed fluorescence emitter in hyperfluorescence OLEDs, providing narrow EL spectra and excellent ηext,maxs of up to 33.8 % with low efficiency roll-offs. The splendid comprehensive performances demonstrate the significant application potential of these AIDF luminogens as both light-emitting materials and sensitizers for OLEDs.

Advances in Host-Free White Organic Light-Emitting Diodes Utilizing Thermally Activated Delayed Fluorescence: A Comprehensive Review

The ever-growing prominence and widespread acceptance of organic light-emitting diodes (OLEDs), particularly those employing thermally activated delayed fluorescence (TADF), have firmly established them as formidable contenders in the field of lighting technology. TADF enables achieving a 100% utilization rate and efficient luminescence through reverse intersystem crossing (RISC). However, the effectiveness of TADF-OLEDs is influenced by their high current density and limited device lifetime, which result in a significant reduction in efficiency. This comprehensive review introduces the TADF mechanism and provides a detailed overview of recent advancements in the development of host-free white OLEDs (WOLEDs) utilizing TADF. This review specifically scrutinizes advancements from three distinct perspectives: TADF fluorescence, TADF phosphorescence and all-TADF materials in host-free WOLEDs. By presenting the latest research findings, this review contributes to the understanding of the current state of host-free WOLEDs, employing TADF and underscoring promising avenues for future investigations. It aims to serve as a valuable resource for newcomers seeking an entry point into the field as well as for established members of the WOLEDs community, offering them insightful perspectives on imminent advancements.

Creation of High-Quality Deep-Blue AIE Emitter with a Crossed Long-Short Axis Structure for Efficient and Versatile OLEDs

Developing deep-blue emitters for organic light-emitting diodes (OLEDs) is critical but challenging, which requires a good balance between light color, exciton utilization, and photoluminescence quantum yield (PLQY) of solid film. Herein, a high-quality deep-blue emitter, abbreviated 2TriPE-CzMCN, is designed by introducing an aggregation-induced emission (AIE) group into a crossed long-short axis (CLSA) skeleton. Theoretical and experimental investigations reveal that the CLSA molecular design can achieve a balance between deep-blue emission and triplet-excitons utilization, while the high PLQY of the solid film resulting from the AIE feature helps to improve the performance of OLEDs. Consequently, when 2TriPE-CzMCN is used as the emitting dopant, the OLED exhibits a deep-blue emission at 430 nm with a record-high maximum external quantum efficiency (EQE) of 8.84%. When 2TriPE-CzMCN serves as the host material, the sensitized monochrome orange and two-color white OLEDs (WOLEDs) realize high EL performances that exceed the efficiency limit of conventional fluorescent OLEDs. Moreover, high-performance three-color WOLEDs with a color rendering index (CRI) exceeding 90 and EQE up to 18.08% are achieved by using 2TriPE-CzMCN as the blue-emitting source. This work demonstrates that endowing CLSA molecule with AIE feature is an effective strategy for developing high-quality deep-blue emitters, and high-performance versatile OLEDs can be realized through rational device engineering.

High-efficiency crystalline white organic light-emitting diodes

Crystalline white organic light-emitting diodes (C-WOLEDs) are promising candidates for lighting and display applications. It is urgently necessary, however, to develop energy-saving and high-efficiency C-WOLEDs that have stable and powerful emission to meet commercial demands. Here, we report a crystalline host matrix (CHM) with embedded nanoaggregates (NA) structure for developing high-performance C-WOLEDs by employing a thermally activated delayed fluorescence (TADF) material and orange phosphorescent dopants (Phos.-D). The CHM-TADFNA-D WOLED exhibit a remarkable EQE of 12.8%, which is the highest performance WOLEDs based on crystalline materials. The device has a quick formation of excitons and a well-designed energy transfer process, and possesses a fast ramping of luminance and current density. Compared to recently reported high-performance WOLEDs based on amorphous material route, the C-WOLED achieves a low series-resistance Joule-heat loss ratio and an enhanced photon output, demonstrating its significant potential in developing the next-generation WOLEDs.

White Light Emission via Dual Thermally Activated Delayed Fluorescence from a Single-Component Phenothiazines-Diphenyl Quinoline Conjugate

White light emission (WLE) via dual thermally activated delayed fluorescence (TADF) from a single-component-based organic system remains challenging as a result of the difficulty in design. Here, we introduce a conformational isomerization approach to achieve WLE from a twisted donor-acceptor (PTzQP1) that comprises two phenothiazines covalently attached to the 6,8-isomeric positions of 2,4-diphenyl quinoline via two C-N single bonds. Spectroscopic studies and quantum chemistry calculations revealed that PTzQP1 shows WLE via simultaneous blue TADF and orange TADF covering the visible range (420-800 nm) with a photoluminescence quantum yield of 45 ± 2% and Commission Internationale de l'Éclairage (CIE) coordinates of 0.30, 0.33. The dual TADF features with high rates of reverse intersystem crossing (kRISC1 = 1.38 × 107 ± 0.24 s-1 and kRISC2 = 5.04 × 106 ± 0.32 s-1) are realized as a result of the low singlet-triplet gaps (S1EQ-T1EQ = 0.04 eV and S1QA-T1QA = 0.05 eV) of the quasi-axial (QA) and quasi-equatorial (QE) conformers. This finding is expected to provide a new direction for designing high-energy-efficient WLE emitters.

Simultaneously Realizing High Efficiency and High Color Rendering Index for Hybrid White Organic Light-Emitting Diodes by Ultra-Thin Design of Delayed Fluorescence Sensitized Phosphorescent Layers

In consideration of energy economization and light quality, concurrently attaining high external quantum efficiency (ηext ) and high color rendering index (CRI) is of high significance for the commercialization of hybrid white organic light-emitting diodes (WOLEDs) but is challenging. Herein, a blue luminescent molecule (2PCz-XT) consisting of a xanthone acceptor and two 3,6-diphenylcarbazole donors is prepared, which exhibits strong delayed fluorescence, short delayed fluorescence lifetime, and excellent electroluminescence property, and can sensitize green, orange, and red phosphorescent emitters efficiently. By employing 2PCz-XT as sensitizer and phosphorescent emitters as dopants, efficient two-color and three-color WOLED architectures with ultra-thin phosphorescent emitting layers (EMLs) are proposed and constructed. By incorporating a thin interlayer to modulate exciton recombination zone and reduce exciton loss, high-performance three-color hybrid WOLEDs are finally achieved, providing a high ηext of 26.8% and a high CRI value 83 simultaneously. Further configuration optimization realizes a long device operational lifetime. These WOLEDs with ultra-thin phosphorescent EMLs are among the state-of-the-art hybrid WOLEDs in the literature, demonstrating the success and applicability of the proposed device design for developing robust hybrid WOLEDs with superb efficiency and color quality.

Rational Medium-Range Charge Transfer Strategy Toward Highly Efficient Violet-Blue Organic Light-Emitting Diodes with Narrowed Emission

The spectral narrowing engineering of pure-organic emitters attracts great research interests in realizing high color purity. Here, the adjusted medium-range charge transfer (MCT) strategy of TIC-BO with rigid planar structure by fusing two typical UV-emitting multiple resonance (MR) fragments via the ingenious double-halide cyclized coupling reaction is reported. The resulting TIC-BO with MCT nature shows efficient violet-blue emission in dilute toluene and evaporated host-guest films, and desirably narrowed spectra are achieved by the suppression of structural relaxation and the shortened charge transfer states. The single-doped device with TIC-BO as emitter shows narrowed violet-blue electroluminescence peaked at 428 nm with full-width at half-maximum of 43 nm (0.28 eV), and the Commission Internationale de l'Éclairage coordinates of (0.160, 0.050). A maximum external quantum efficiency (EQEmax ) of 20.50% is achieved, which is among the best results of the corresponding violet-blue emitting region. Further introduction of a stronger electron-donating carbazole group makes TIC-BNO exhibit red-shifted sky-blue emission with MR-dominant properties, and good device performance is received with EQEmax of 34.58%. The outstanding performances of TIC-BO successfully demonstrate the significance and prospect of the proposed molecular design strategy.

High-efficiency all-fluorescent white organic light-emitting diode based on TADF material as a sensitizer

The use of TADF materials as both sensitizers and emitters is a promising route to achieve high-efficiency all-fluorescent white organic light-emitting diodes (WOLEDs). In this study, the thermally-activated delayed-fluorescent (TADF) material DMAC-TRZ (9,9-dimethyl-9,10-dihydroacridine-2,4,6-triphenyl-1,3,5-triazine) was selected as a sensitizer for the conventional fluorescent emitter DCJTB (4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran), which was co-doped in a wide bandgap host of DPEPO (bis[2-(diphenylphosphino)phenyl]ether oxide) to fabricate WOLEDs. For the emitting layer of DPEPO:DMAC-TRZ:DCJTB, the DPEPO host can dilute the exciton concentration formed on the DMAC-TRZ sensitizer, which benefits the suppression of exciton quenching. The effect of the doping concentration of DCJTB on the carrier recombination and energy transfer process was investigated. With an optimized doping concentration of DCJTB as 0.8%, highly efficient WOLED was achieved with a maximum external quantum efficiency (EQE), power efficiency (PE), and current efficiency (CE) of 11.05%, 20.83 lm W-1, and 28.83 cd A-1, respectively, corresponding to the Commission Internationale de I' Eclairage (CIE) coordinates of (0.45, 0.46). These superior performances can be ascribed to the fact that the hole-trapping effect of the emitter and Dexter energy transfer (DET) from sensitizer to emitter can be suppressed simultaneously by the extremely low doping concentration.

High-efficiency all fluorescence white OLEDs with high color rendering index by manipulating excitons in co-host recombination layers

All fluorescence white organic light-emitting diodes (WOLEDs) based on thermally activated delayed fluorescence (TADF) emitters are an attractive route to realize highly efficient and high color quality white light sources. However, harvesting triplet excitons in these devices remains a formidable challenge, particularly for WOLEDs involving conventional fluorescent emitters. Herein, we report a universal design strategy based on a co-host system and a cascaded exciton transfer configuration. The co-host system furnishes a broad and charge-balanced exciton generation zone, which simultaneously endows the devices with low efficiency roll-off and good color stability. A yellow TADF layer is put forward as an intermediate sensitizer layer between the blue TADF light-emitting layer (EML) and the red fluorescence EML, which not only constructs an efficient cascaded Förster energy transfer route but also blocks the triplet exciton loss channel through Dexter energy transfer. With the proposed design strategy, three-color all fluorescence WOLEDs reach a maximum external quantum efficiency (EQE) of 22.4% with a remarkable color rendering index (CRI) of 92 and CIE coordinates of (0.37, 0.40). Detailed optical simulation confirms the high exciton utilization efficiency. Finally, by introducing an efficient blue emitter 5Cz-TRZ, a maximum EQE of 30.1% is achieved with CIE coordinates of (0.42, 0.42) and a CRI of 84 at 1000 cd m-2. These outstanding results demonstrate the great potential of all fluorescence WOLEDs in solid-state lighting and display panels.

Tröger's Base-Derived Thermally Activated Delayed Fluorescence Dopant for Efficient Deep-Blue Organic Light-Emitting Diodes

The development of efficient deep-blue emitters with thermally activated delayed fluorescence (TADF) properties is a highly significant but challenging task in the field of organic light-emitting diode (OLED) applications. Herein, we report the design and synthesis of two new 4,10-dimethyl-6H,12H-5,11-methanodibenzo[b,f][1,5]diazocine (TB)-derived TADF emitters, TB-BP-DMAC and TB-DMAC, which feature distinct benzophenone (BP)-derived acceptors but share the same dimethylacridin (DMAC) donors. Our comparative study reveals that the amide acceptor in TB-DMAC exhibits a significantly weaker electron-withdrawing ability in comparison to that of the typical benzophenone acceptor employed in TB-BP-DMAC. This disparity not only causes a noticeable blue shift in the emission from green to deep blue but also enhances the emission efficiency and the reverse intersystem crossing (RISC) process. As a result, TB-DMAC emits efficient deep-blue delay fluorescence with a photoluminescence quantum yield (PLQY) of 50.4% and a short lifetime of 2.28 μs in doped film. The doped and non-doped OLEDs based on TB-DMAC display efficient deep-blue electroluminescence with spectral peaks at 449 and 453 nm and maximum external quantum efficiencies (EQEs) of 6.1% and 5.7%, respectively. These findings indicate that substituted amide acceptors are a viable option for the design of high-performance deep-blue TADF materials.

Energy-Efficient Stable Hyperfluorescence Organic Light-Emitting Diodes with Improved Color Purities and Ultrahigh Power Efficiencies Based on Low-Polar Sensitizing Systems

Multi-resonance (MR) molecules with thermally activated delayed fluorescence (TADF) are emerging as promising candidates for high-definition displays because of their narrow emission spectra. However, the electroluminescence (EL) efficiencies and spectra of MR-TADF molecules are highly sensitive to hosts and sensitizers when applied to organic light-emitting diodes (OLEDs), and the highly polar environments in devices often lead to significantly broadened EL spectra. In this study, a proof-of-concept TADF sensitizer (BTDMAC-XT) with low polarity, high steric hindrance, and concentration-quenching free feature is constructed, which acts as a good emitter in doped and non-doped OLEDs with high external quantum efficiencies (η_ext s) of 26.7% and 29.3%, respectively. By combining BTDMAC-XT with conventional low-polarity hosts, low-polarity sensitizing systems with a small carrier injection barrier and full exciton utilization are constructed for the MR-TADF molecule BN2. Hyperfluorescence (HF) OLEDs employing the low-polar sensitizing systems successfully improve the color quality of BN2 and afford an excellent η_ext of 34.4%, a record-high power efficiency of 166.3 lm W^-1 and a long operational lifetime (LT₅₀  = 40309 h) at an initial luminance of 100 cd m^-2 . These results provide instructive guidance for the sensitizer design and device optimization for energy-efficient and stable HF-OLEDs with high-quality light.

Realizing efficient blue and deep-blue delayed fluorescence materials with record-beating electroluminescence efficiencies of 43.4

As promising luminescent materials for organic light-emitting diodes (OLEDs), thermally activated delayed fluorescence materials are booming vigorously in recent years, but robust blue ones still remain challenging. Herein, we report three highly efficient blue and deep-blue delayed fluorescence materials comprised of a weak electron acceptor chromeno[3,2-c]carbazol-8(5H)-one with a rigid polycyclic structure and a weak electron donor spiro[acridine-9,9'-xanthene]. They hold distinguished merits of excellent photoluminescence quantum yields (99%), ultrahigh horizontal transition dipole ratios (93.6%), and fast radiative transition and reverse intersystem crossing, which furnish superb blue and deep-blue electroluminescence with Commission Internationale de I'Eclairage coordinates (CIE_x,y) of (0.14, 0.18) and (0.14, 0.15) and record-beating external quantum efficiencies (η_exts) of 43.4% and 41.3%, respectively. Their efficiency roll-offs are successfully reduced by suppressing triplet-triplet and singlet-singlet annihilations. Moreover, high-performance deep-blue and green hyperfluorescence OLEDs are achieved by utilizing these materials as sensitizers for multi-resonance delayed fluorescence dopants, providing state-of-the-art η_exts of 32.5% (CIE_x,y = 0.14, 0.10) and 37.6% (CIE_x,y = 0.32, 0.64), respectively, as well as greatly advanced operational lifetimes. These splendid results can surely inspire the development of blue and deep-blue luminescent materials and devices.

Progresses and Perspectives of Near-Infrared Emission Materials with "Heavy Metal-Free" Organic Compounds for Electroluminescence

Organic/polymer light-emitting diodes (OLEDs/PLEDs) have attracted a rising number of investigations due to their promising applications for high-resolution fullcolor displays and energy-saving solid-state lightings. Near-infrared (NIR) emitting dyes have gained increasing attention for their potential applications in electroluminescence and optical imaging in optical tele-communication platforms, sensing and medical diagnosis in recent decades. And a growing number of people focus on the "heavy metal-free" NIR electroluminescent materials to gain more design freedom with cost advantage. This review presents recent progresses in conjugated polymers and organic molecules for OLEDs/PLEDs according to their different luminous mechanism and constructing systems. The relationships between the organic fluorophores structures and electroluminescence properties are the main focus of this review. Finally, the approaches to enhance the performance of NIR OLEDs/PLEDs are described briefly. We hope that this review could provide a new perspective for NIR materials and inspire breakthroughs in fundamental research and applications.