Unraveling non-radiative decay channels of exciplexes to construct efficient red emitters for organic light-emitting diodes.

Exciplex emitters naturally have thermally activated delayed fluorescence characteristics due to their spatially separated molecular orbitals. However, the intermolecular charge transfer potentially induces diverse non-radiative decay channels, severely hindering the construction of efficient red exciplexes. Thus, a thorough comprehension of this energy loss is of paramount importance. Herein, different factors, including molecular rigidity, donor-acceptor interactions and donor-donor/acceptor-acceptor interactions, that impact the non-radiative decay were systematically investigated using contrasting exciplex emitters. The exciplex with rigid components and intermolecular hydrogen bonds showed a photoluminescence quantum yield of 84.1% and a singlet non-radiative decay rate of 1.98 × 106 s-1 at an optimized mixing ratio, respectively, achieving a 3.3-fold increase and a 70% decrease compared to the comparison group. In the electroluminescent device, a maximum external quantum efficiency of 23.8% was achieved with an emission peak of 608 nm, which represents the state-of-the-art organic light-emitting diodes using exciplex emitters. Accordingly, a new strategy is finally proposed, exploiting system rigidification to construct efficient red exciplex emitters that suppress non-radiative decay.

Comparative analysis of psychiatric medications and their association with falls and fractures: A systematic review and network meta-analysis.

An association between psychiatric medications and falls and fractures in people taking them has been demonstrated, but which class or medication leads to the greatest risk of falls or fractures should be further investigated. The aim of this study was to compare and rank the magnitude of risk of falls and fractures due to different psychiatric medications. Eight databases were searched for this meta-analysis and evaluated using a frequency-based network meta-analysis. The results included a total of 28 papers with 14 medications from 5 major classes, involving 3,467,314 patients. The results showed that atypical antipsychotics were the class of medications with the highest risk of falls, and typical antipsychotics were the class of medications with the highest risk of resulting in fractures. Quetiapine ranked first in the category of 13 medications associated with risk of falls, and class Z drugs ranked first in the category of 6 medications associated with risk of fractures. The available evidence suggests that atypical antipsychotics and typical antipsychotics may be the drugs with the highest risk of falls and fractures, respectively. Quetiapine may be the medication with the highest risk of falls, and class Z drugs may be the medication with the highest risk of fractures.

A high-performance dual-functional organic upconversion device with detectivity approaching 1013 Jones and photon-to-photon efficiency over 20.

Organic upconversion devices (UCDs) are a cutting-edge technology and hot topic because of their advantages of low cost and convenience in the important applications of near-infrared (NIR) detection and imaging. However, to realize utilization of triplet excitons (T1), previous UCDs have the drawback of heavily relying on toxic and costly heavy-metal-doped emitters. More importantly, due to poor performance of the detecting unit and/or emitting unit, improving their detectivity (D*) and photon-to-photon conversion efficiency (ηp-p) is still a challenge for real applications. Here, we report a high-performance dual-functional purely organic UCD that has an outstanding D* approaching 1013 Jones and a high ηp-p of 20.1% in the NIR region, which are some of the highest values among those reported for UCDs. The high performance is credited to the excellent D* of the detecting unit, exceeding 1014 Jones, and is also attributed to efficient T1 utilization via a dual reverse intersystem crossing channel and high optical out coupling achieved via a high horizontal dipole ratio in the emitting unit. The high D* and ηp-p enable the UCD to detect 850 nm light at as little as 0.29 µW cm-2 and with a high display contrast of over 70 000 : 1, significantly improving the potential of practical applications of UCDs in NIR detection and imaging. Furthermore, a fast rise time and fall time of 8.9 and 14.8 µs are also achieved. Benefiting from the high performance, consequent applications of low-power pulse-state monitoring and fine-structure bio-imaging are successfully realized with high quality results by using our organic UCDs. These results demonstrate that our design not only eliminates dependence of UCDs on heavy-metal emitters, but also takes their performance and applications to a high level.

Highly Efficient OLEDs by Using a Brominated Thermally Activated Delayed Fluorescent Host due to Balanced Carrier Transport and Enhanced Exciton Upconversion.

Thermally activated delayed fluorescent (TADF) materials are naturally bipolar and can potentially serve as hosts. However, triplet excitons in TADF materials are long-lived and prone to unfavorable bimolecular processes. Implementing an efficient reverse system intersection (RISC) process is an effective solution. Moreover, although the general TADF host is bipolar, polarity differences still cause a mobility imbalance. In this work, we designed and synthesized a novel TADF host material, 11-(3-(4-(3-bromophenyl)-6-phenyl-1,3,5-triazin-2-yl)phenyl)-12,12-dimethyl-11,12-dihydroindeno[2,1-a]carbazole (Br-DMIC-TRZ). The upconversion of the TADF host and its doped films is facilitated due to enhanced spin-orbit coupling (SOC) induced by bromine, which exhibits a higher rate of RISC. This progress facilitates the involvement of more triplet excitons in luminescence. Meanwhile, the attachment of bromine to the acceptor fragment of TADF enhances the electron mobility, where hole mobility and electron mobility are more comparable. Enhanced exciton upconversion and balanced carrier transport allow devices formed based on brominated TADF hosts to outperform other hosts. The Br-TADF-based devices with three dopants sensitized achieved improvements of 29.8, 21.4, and 24.4% compared to the DMIC-TRZ-based device. This work provides a feasible molecular design strategy for further developing efficient hosts.

Efficient Near-Infrared Organic Photodetectors with Spectral Response up to 1600 nm for Accurate Alcohol Concentration Detection.

The development of near-infrared organic photodetectors (NIR-OPDs) in 1000-1700 nm is essential for medical monitoring, food quality inspection, machine vision, and biomedical imaging. However, when solving the high dark current density (JD) in bulk-heterojunction (BHJ) NIR-OPDs based on narrow-bandgap systems, it is often accompanied by photocurrent loss, which is a great challenge in achieving high-performance NIR-OPDs. Here, an ideal hybrid pseudo-PHJ (planar-heterojunction)/BHJ structure is proposed to overcome this challenge, which is introducing the N2200 layer between the cathode and BHJ. The introduction of the N2200 raises the external charge injection barrier and reduces the trap density, thus achieving significant suppression of JD (6.22 × 10-7 A cm-2 at -0.2 V bias, about 2 orders of magnitude lower compared to the BHJ NIR-OPDs). Meanwhile, the hybrid structure combines the advantages of PHJ and BHJ, thus maintaining a high photocurrent, resulting in responsivity and detectivity of 18.71 mA W-1 and 4.19 × 1010 Jones, respectively, at 1400 nm at -0.2 V bias, which is superior to the performance of BHJ NIR-OPDs. And the hybrid structured NIR-OPDs are proven to rapidly quantify the alcohol content of mixtures to within 2% accuracy, which exhibits great potential for application in the food and pharmaceutical industries.

High-Quality Artery Monitoring and Pathology Imaging Achieved by High-Performance Synchronous Electrical and Optical Output of Near-Infrared Organic Photodetector.

Near-infrared organic photodetectors (NIR-OPDs) are significant technologies in emerging biomedicine applications for uniquely wearable, noninvasive, low-cost advantages. However, biosignals are weak and changing rapidly so practical biodetection and bioimaging are still challenging for NIR-OPDs. Herein, high-performance NIR-OPDs with synchronous optical output are realized by recombining anode-injected electrons with photogenerated holes on emitters. Owing to high detection performance of 4.5 × 1012 Jones detectivity and 120 kHz -3 dB bandwidth, five arteries are monitored by transmission-type method and cardiac cycle is analyzed. Importantly, the synchronous optical output is direct emission demonstrating outstanding photon conversion efficiency approaching 20% and luminance signal-to-noise ratio over 8000. Consequently, pathology imaging is directly developed without complex readout circuits and arrays from which squamous metaplasia of cervix and carcinoma of large intestine are observed clearly. The NIR-OPD demonstrates strategies for high-performance synchronous electrical/optical output and directly imaging. Biomedicine applications implemented here are high level, representing important steps for NIR-OPDs toward providing clues for clinical diagnosis.

High-performance organic upconversion device with 12% photon to photon conversion efficiency at 980†nm and bio-imaging application in near-infrared region.

We demonstrated an organic upconversion device (UCD) successfully converted input NIR light (850-1310 nm) into 524 nm green emission. The UCD under 980 nm light irradiation exhibits a high photon to photon conversion efficiency of 12%. In addition, the linear dynamic range reaches 72.1 dB and the maximum on/off ratio of luminance reaches 4.4×104, which guarantee the clarity of imaging from 850 to 1310 nm. The UCD in this work has the characteristics of high efficiency and long wavelengths detection, and it makes some senses for long wavelengths NIR bio-imaging in further researches.

Novel Dark Current Reduction Strategy via Deep Bulk Traps for High-Performance Solution-Processed Organic Photodetectors.

The performance improvement of the organic photodetectors (OPDs) focuses on suppressing the dark current density (Jd) to improve the specific detectivity. In this work, a dark current reduction strategy relying on constructing limited deep traps in the active layer to suppress charge injection rate was newly proposed. And an optimization method has been successfully demonstrated on the solution-processed OPDs accordingly. Compared with the Jd expressed by the OPD with the shallow trap system, the device with deep bulk traps exhibits a dramatically reduced dark current while ensuring high responsivity. At a bias of -2 V, the optimized photodiode with a Jd down to 1.4 × 10-5 mA cm-2 and a maximum responsivity of 0.42 A W-1 @620 nm was realized, leading to a maximum detectivity calculated from shot noise of 6.23 × 1012 Jones. This value is 49-fold higher than that of the original OPD with the same structure. The effects of deep traps inside the semiconductor film on injected carriers and photogenerated carriers are well explained by the relative positions of the initial hopping levels. A better understanding of charge transport regimes in OPD helps to open new approaches for constructing high-performance OPD toward practical applications.

A novel orange-red thermally activated delayed fluorescence emitter with high molecular rigidity and planarity realizing 32.5% external quantum efficiency in organic light-emitting diodes.

Simultaneous optimization of photoluminescence quantum yield (ΦPL) and horizontally oriented dipoles (Θ‖) is considerably challenging for orange and red thermally activated delayed fluorescence (TADF) emitters, due to the conflicts between enhancing molecular rigidity and improving molecular planarity. Herein, a novel orange-red TADF emitter 10-(dipyrido[3,2-a:2',3'-c]phenazin-11-yl)-10H-spiro[acridine-9,9'-fluorene] (SAF-2NP) was constructed with a donor-acceptor structure. The highly rigid donor and acceptor segments ensure the overall rigidity of the emitter. More importantly, the quasi-coplanar structure between the acceptor and the fluorene moiety in the donor unit enlarges the molecular plane without weakening rigidity. Consequently, SAF-2NP exhibited extremely high ΦPL and Θ‖ of 99% and 85%, respectively. The optimal organic light-emitting diode using SAF-2NP as the emitter and 4,4'-di(9H-carbazol-9-yl)-1,1'-biphenyl (CBP) as the host demonstrated an unparalleled external quantum efficiency of 32.5% and a power efficiency of 85.2 lm W-1 without any extra light extraction structure. This work provides a feasible strategy to establish efficient orange and red TADF emitters with both high rigidity and planarity.

Additive-Induced Vertical Component Distribution Enables High-Performance Sequentially Cast Organic Solar Cells.

Modulation of the active layer morphology to form a vertical component distribution structure is an effective way of improving the efficiency of organic solar cells (OSCs). In this paper, a layer-by-layer (LbL) spin-coating method was adopted combined with an additive strategy to achieve the purpose of precisely adjusting the morphology, and finally, high-performance OSCs based on a D18-Cl/Y6 system were achieved. After adding n-octane in D18-Cl, D18-Cl+/Y6 devices realized a PCE of 17.70%, while with the incorporation of 1-fluoronaphthalene (FN) in Y6, D18-Cl/Y6+ devices obtained a power conversion efficiency (PCE) of 17.39%, both higher than the control devices (16.66%). The former resulted in a more orderly arrangement of D18-Cl, forming a suitable phase separation morphology, and the latter improved the crystallization of Y6, which facilitated carrier transport. Furthermore, the dual-additive-treated D18-Cl+/Y6+ bilayer devices with n-octane doping in the donor and FN in the acceptor had a more desirable vertical morphology, exhibiting an excellent PCE of 18.16% with an improved JSC of 27.17 mA cm-2 and FF of 76.88%, one of the highest efficiencies for LbL OSCs. The results demonstrated that combining the LbL spin-coating method with the additive strategy is a valid way to achieve hierarchical morphology control and enhance device performance, which is of great significance for the fabrication and development of OSCs.

Thermally activated delayed fluorescence exciplex emitters for high-performance organic light-emitting diodes.

Owing to their natural thermally activated delayed fluorescence (TADF) characteristics, the development of exciplex emitters for organic light-emitting diodes (OLEDs) has witnessed booming progress in recent years. Formed between electron-donating and electron-accepting molecules, exciplexes with intermolecular charge transfer processes have unique advantages compared with unimolecular TADF materials, offering a new way to develop high-performance TADF emitters. In this review, a comprehensive overview of TADF exciplex emitters is presented with a focus on the relationship between the constituents of exciplexes and their electroluminescence performance. We summarize and discuss the latest and most significant developments of TADF exciplex emitters. Notably, the design principles of efficient TADF exciplex emitters are systematically categorized into three systems within this review. These progressive achievements of TADF exciplex emitters point out future challenges to trigger more research endeavors in this growing field.

Efficient Organic Upconversion Devices for Low Energy Consumption and High-Quality Noninvasive Imaging.

Infrared upconversion devices (UCDs) enable low-cost visualization of infrared optical signals without utilizing a readout circuit, which is of great significance for biological recognition and noninvasive dynamic monitoring. However, UCDs suffer from inferior photon to photon (p-p) efficiency and high turn-on voltage (Von ) for upconversion operation, hindering a further expansion in highly resolved infrared imaging. Herein, an efficient organic UCD integrating an interfacial exciplex emitter and a well-designed near-infrared (NIR) detector reveals a high efficiency up to 12.92% and a low Von down to 1.56 V. The low Von gives the capacity for detecting weak NIR light down to 3.2 µW cm-2 , significantly expanding the detection power scale of UCDs. Thus, the imaging linear dynamic range (I-LDR) is highly bias-tunable, ranging from 13.23 to 84.4 dB. The high I-LDR enables highly resolved and strong-penetration bioimaging especially for thick biological sections, indicating great potential in noninvasive defect and pathological detection.

Recovering the Thermally Activated Delayed Fluorescence in Aggregation-Induced Emitters of Carborane.

The aggregation-induced emission (AIE) behaviors of carborane-based hybrid emitters have been extensively reported, while their combinations with the thermally activated delayed fluorescence (TADF) are still scarce. We designed and synthesized three Janus carboranes (the chemical structures resemble the double-faced god, Janus) Cb-1/2/3 with different carbazole moieties. All of the Janus carboranes exhibited quenched emission in solution with ΦPL (quantum efficiency of photoluminescence (PL)) lower than 0.01. The PL performance was improved by proceeding to the aggregates in THF/water (ΦPL 0.17-0.35) and further improved in the crystals or solid with ΦPL up to 0.99 for Cb-1, 0.85 for Cb-2, and 0.61 for Cb-3, which agreed with the AIE enhancement. Although the PL of solid Cb-1/2/3 showed non-TADF properties with lifetimes only at several nanoseconds, the crystallographic studies have shown a root cause of π···π stacking that quenched the TADF, and the theoretical calculations forecasted small singlet-triplet energy gaps (ΔES-T) therein. According to these findings, TADF was recovered in Cb-1/2/3 by doping into 1,3-bis(carbazol-9-yl)benzene (mCP). The 10 wt % doped films of Cb-1/2/3 have achieved a trade-off of ΦPL (0.84 in Cb-3 and 0.83 in Cb-1) and delayed lifetime (up to 8 µs). The doped devices of organic light-emitting diodes incorporating Cb-1/2/3 achieved the highest external quantum efficiency at 10.1% and the maximized luminance of 5920 cd/m2 at a driving voltage of 8 V.

Efficient Exciplex-based Green and Near-Infrared Organic Light-Emitting Diodes Employing a Novel Donor-Acceptor Type Donor.

Widely investigated thermally activated delayed fluorescence (TADF) can be achieved by intramolecular and intermolecular charge transfer between an electron donor and electron acceptor which corresponds to a TADF material and exciplex, respectively. However, the development of efficient organic light-emitting diodes (OLEDs) based on an exciplex lags far behind the development of those based on efficient TADF materials. In this work, a novel D-A type electron donor TPAFPO was designed and synthesized. TPAFPO:PO-T2T exhibits a small ΔEST of 79 meV and significant delayed emission, demonstrating TADF characteristics. OLEDs based on TPAFPO:PO-T2T exhibit a low turn-on voltage of 2.4 V and high an EQE value of 17.0%. Besides, NIR OLEDs utilizing TPAFPO:PO-T2T as host exhibit a turn-on voltage of 3.0 V and high EQE of 9.2% with a NIR emission peak at 690 nm. Furthermore, solution-processed exciplex and NIR devices also can maintain high efficiencies of 15.1% and 8.1%, respectively.

Introducing Trifluoromethyl to Strengthen Hydrogen Bond for High Efficiency Organic Solar Cells.

Nowadays, the ternary strategy has become a common way to improve the power conversion efficiency (PCE) of organic solar cells (OSCs). The intermolecular interaction between the third component and donor or acceptor plays a key role in achieving a high performance. However, hydrogen bond as a strong intermolecular interaction is rarely considered in ternary OSCs. In this work, we introduce trifluoromethyl on a newly synthesized small molecular DTBO to strength hydrogen bonds between DTBO and IEICO-4F. Due to the existence of hydrogen bonds has a strong impact on electrostatic potential (ESP) and benefits π-π stacking in the active layer, the ternary OSCs show superior charge extraction and low charge recombination. In DTBO, PTB7-Th and IEICO-4F based ternary devices, the PCE increases from 11.02 to 12.48%, and short-circuit current density (J SC ) increases from 24.94 to 26.43 mA/cm2 compared with typical binary devices. Moreover, the addition of DTBO can realize an energy transfer from DTBO to PTB7-Th and broaden the absorption spectrum of blend films. Grazing-incidence wide-angle X-ray scattering (GIWAXS) patterns show that the π-π stacking distance of IEICO-4F decreased after adding 10 wt% DTBO. The effect of the hydrogen bond is also achieved in the PM6: Y6 system, showing 16.64% efficiency by comparison to the 15.49% efficiency of binary system. This work demonstrates that introduce trifluoromethyl to enhance hydrogen bond which improve π-π stacking can achieve higher performance in OSCs.

Imidazo[1,2-a]pyridine as an Electron Acceptor to Construct High-Performance Deep-Blue Organic Light-Emitting Diodes with Negligible Efficiency Roll-Off.

Two novel bipolar deep-blue fluorescent emitters, IP-PPI and IP-DPPI, featuring different lengths of the phenyl bridge, were designed and synthesized, in which imidazo[1,2-a]pyridine (IP) and phenanthroimidazole (PI) were proposed as an electron acceptor and an electron donor, respectively. Both of them exhibit outstanding thermal stability and high emission quantum yields. All the devices based on these two materials showed negligible efficiency roll-off with increasing current density. Impressively, non-doped organic light-emitting diodes (OLEDs) based on IP-PPI and IP-DPPI exhibited external quantum efficiencies (EQEs) of 4.85 % and 4.74 % with CIE coordinates of (0.153, 0.097) and (0.154, 0.114) at 10000 cd m-2 , respectively. In addition, the 40 wt % IP-PPI doped device maintained a high EQE of 5.23 % with CIE coordinates of (0.154, 0.077) at 10000 cd m-2 . The doped device based on 20 wt % IP-DPPI exhibited a higher deep-blue electroluminescence (EL) performance with a maximum EQE of up to 6.13 % at CIE of (0.153, 0.078) and maintained an EQE of 5.07 % at 10000 cd m-2 . To the best of our knowledge, these performances are among the state-of-the art devices with CIEy ≤0.08 at a high brightness of 10000 cd m-2 . Furthermore, by doping a red phosphorescent dye Ir(MDQ)2 (MDQ=2-methyldibenzo[f,h]quinoxaline) into the IP-PPI and IP-DPPI hosts, high-performance red phosphorescent OLEDs with EQEs of 20.8 % and 19.1 % were achieved, respectively. This work may provide a new approach for designing highly efficient deep-blue emitters with negligible roll-off for OLED applications.

Tricomponent Exciplex Emitter Realizing over 20% External Quantum Efficiency in Organic Light-Emitting Diode with Multiple Reverse Intersystem Crossing Channels.

With the naturally separated frontier molecular orbitals, exciplexes are capable of thermally activated delayed fluorescence emitters for organic light-emitting diodes (OLEDs). And, the current key issue for exciplex emitters is improving their exciton utilization. In this work, a strategy of building exciplex emitters with three components is proposed to realize multiple reverse intersystem crossing (RISC) channels, improving their exciton utilization by enhancing upconversion of nonradiative triplet excitons. Accordingly, a tricomponent exciplex DBT-SADF:PO-T2T:CDBP is constructed with three RISC channels respectively on DBT-SADF, DBT-SADF:PO-T2T, and CDBP:PO-T2T. Furthermore, its photoluminescence quantum yield and rate constant of the RISC process are successfully improved. In the OLED, DBT-SADF:PO-T2T:CDBP exhibits a remarkably high maximum external quantum efficiency (EQE) of 20.5%, which is the first report with an EQE over 20% for the OLEDs based on exciplex emitters to the best of our knowledge. This work not only demonstrates that introducing multiple RISC channels can effectively improve the exciton utilization of exciplex emitters, but also proves the superiority of the tricomponent exciplex strategy for further development of exciplex emitters.

Ternary System with Intermolecular Hydrogen Bond: Efficient Strategy to High-Performance Nonfullerene Organic Solar Cells.

To boost organic solar cell (OSC) performance, numerous approaches have been developed, such as synthesizing new materials, using post-annealing (thermal or solvent annealing) or fabricating ternary devices. The ternary strategy is usually used as an uncomplicated and effective way, but how to choose the third component and the effect of interactions between materials on OSC performance still need to be clarified. Herein, we proposed a new finding that the carbonyl group of 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2',3'-d']-s-indaceno[1,2-b:5,6-b'] dithiophene (ITIC) end groups can react with the dye molecule SR197 to form the N-H···O noncovalent interaction. The existence of intermolecular hydrogen bonds was confirmed using Fourier transform infrared spectra and two-dimensional proton nuclear magnetic resonance. The power conversion efficiency (PCE) was improved to 10.29% via doping SR197 into blends of PTB7-Th:ITIC, which exhibited a huge enhancement of approximately 30% compared with the binary OSCs (PCE = 7.92%). The ternary OSCs of PBDB-T:SR197:ITIC could also achieve high PCE (11.03%) without post-thermal or solvent annealing. Transmission electron microscopy and grazing-incidence wide-angle X-ray scattering showed the optimized morphology and enhanced crystallinity of ternary systems, which is facilitated to exciton dissociation and charge transmission. These conclusions mean that the H-bonding strategy is an effective way for selecting the third component and could achieve high-performance OSCs.

Highly Efficient Thermally Activated Delayed Fluorescence Emitter Developed by Replacing Carbazole With 1,3,6,8-Tetramethyl-Carbazole.

Carbazole (Cz) is the one of the most popular electron donors to develop thermally activated delayed fluorescence (TADF) emitters, but additional groups are generally required in the molecules to enhance the steric hindrance between Cz and electron acceptor segments. To address this issue, we replaced Cz with its derivative 1,3,6,8-tetramethyl-carbazole (tMCz) to develop TADF emitters. Two novel compounds, 6-(4-(carbazol-9-yl)phenyl)-2,4-diphenylnicotinonitrile (CzPN) and 2,4-diphenyl-6-(4- (1,3,6,8-tetramethyl-carbazol-9-yl)phenyl) nicotinonitrile (tMCzPN) were designed and synthesized accordingly. With the same and simple molecular framework, tMCzPN successfully exhibits TADF behavior, while CzPN is a non-TADF fluorophor, as the additional steric hindrance of methyl groups leads to a more twisted structure of tMCzPN. In the organic light-emitting diodes (OLEDs), tMCzPN exhibits extremely high forward-viewing maximum external quantum efficiency of 26.0%, without any light out-coupling enhancement, which is significantly higher than that of 5.3% for CzPN. These results indicate that tMCzPN is an excellent TADF emitter and proves that tMCz is a more appropriate candidate than Cz to develop TADF emitters.

Development of Red Exciplex for Efficient OLEDs by Employing a Phosphor as a Component.

Exciplexes are ideal candidates as effective thermally activated delayed fluorescence (TADF) emitters. However, efficient orange and red TADF exciplexes have been reported seldomly, because their significant non-radiative (NR) decay of excited states lead to unavoidable energy loss. Herein, we propose a novel strategy to construct efficient red TADF exciplexes by introducing phosphor as one component. Due to the strong spin-orbit coupling of heavy metal (e.g., Ir, Pt, et al.) ion cores, the NR decays will be evidently decreased for both singlet and triplet excitons, reducing the undesired exciton waste. Moreover, compared with the conventional exciplexes, phosphorescence plays an important role for such novel exciplexes, further improving the exciton utilization. Based on this strategy, we fabricated a red exciplex containing 1,3,5-triazine-2,4,6-triyl)tris(benzene-3,1-diyl)tris(diphenylphosphine oxide) (PO-T2T) and tris(2-phenylpyridine) iridium(III) (Ir(ppy)3) as components and realize a red emission with a peak at 604 nm, a CIE coordinate of (0.55, 0.44), and a high maximum external quantum efficiency of 5% in organic light-emitting device. This efficiency is 2.6 times higher than that of the device based on the conventional red exciplex emitter, proving the superiority of our novel strategy to construct TADF exciplexes with phosphors.