Solution‐Processible Multi‐component Cyclometalated Iridium Phosphors for High‐Efficiency Orange‐Emitting OLEDs and Their Potential Use as White Light Sources

The synthesis and photophysical studies of several multifunctional phosphorescent iridium(III) cyclometalated complexes consisting of the hole‐transporting carbazole and fluorene‐based 2‐phenylpyridine moieties are reported. All of them are isolated as thermally and morphological stable amorphous solids. Extension of the π‐conjugation through incorporation of electron‐pushing carbazole units to the fluorene fragment leads to bathochromic shifts in the emission profile, increases the highest occupied molecular orbital levels and improves the charge balance in the resulting complexes because of the propensity of the carbazole unit to facilitate hole transport. These iridium‐based triplet emitters give a strong orange phosphorescence light at room temperature with relatively short lifetimes in the solution phase. The photo‐ and electroluminescence properties of these phosphorescent carbazolylfluorene‐functionalized metalated complexes have been studied in terms of the coordinating position of carbazole to the fluorene unit. Organic light‐emitting diodes (OLEDs) using these complexes as the solution‐processed emissive layers have been fabricated which show very high efficiencies even without the need for the typical hole‐transporting layer. These orange‐emitting devices can produce a maximum current efficiency of ～ 30 cd A^–1 corresponding to an external quantum efficiency of ～ 10 % ph/el (photons per electron) and a power efficiency of ～ 14 lm W^–1. The homoleptic iridium phosphors generally outperform the heteroleptic counterparts in device performance. The potential of exploiting these orange phosphor dyes in the realization of white OLEDs is also discussed.     

Highly Efficient Green‐Emitting Phosphorescent Iridium Dendrimers Based on Carbazole Dendrons

Green‐emitting iridium dendrimers with rigid hole‐transporting carbazole dendrons are designed, synthesized, and investigated. With second‐generation dendrons, the photoluminescence quantum yield of the dendrimers is up to 87 % in solution and 45 % in a film. High‐quality films of the dendrimers are fabricated by spin‐coating, producing highly efficient, non‐doped electrophosphorescent organic light‐emitting diodes (OLEDs). With a device structure of indium tin oxide/poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonic acid)/neat dendrimer/1,3,5‐tris(2‐N‐phenylbenzimidazolyl)benzene/LiF/Al, a maximum external quantum efficiency (EQE) of 10.3 % and a maximum luminous efficiency of 34.7 cd A^–1 are realized. By doping the dendrimers into a carbazole‐based host, the maximum EQE can be further increased to 16.6 %. The integration of rigid hole‐transporting dendrons and phosphorescent complexes provides a new route to design highly efficient solution‐processable dendrimers for OLED applications.     

Amorphous Diphenylaminofluorene‐Functionalized Iridium Complexes for High‐Efficiency Electrophosphorescent Light‐Emitting Diodes

Two new phosphorescent iridium(III ) cyclometalated complexes, [Ir(DPA‐Flpy)₃] ( 1 ) and [Ir(DPA‐Flpy)₂(acac)] ( 2 ) ((DPA‐Flpy)H = (9,9‐diethyl‐7‐pyridinylfluoren‐2‐yl)diphenylamine, Hacac = acetylacetone), have been synthesized and characterized. The incorporation of electron‐donating diphenylamino groups to the fluorene skeleton is found to increase the highest occupied molecular orbital (HOMO) levels and add hole‐transporting ability to the phosphorescent center. Both complexes are highly amorphous and morphologically stable solids and undergo glass transitions at 160 and 153 °C, respectively. These iridium phosphors emit bright yellow to orange light at room temperature with relatively short lifetimes (< 1 μs) in both solution and the solid state. Organic light‐emitting diodes (OLEDs) fabricated using 1 and 2 as phosphorescent dopant emitters constructed with a multilayer configuration show very high efficiencies. The homoleptic iridium complex 1 is shown to be a more efficient electrophosphor than the heteroleptic congener 2 . Efficient electrophosphorescence with a maximum external quantum efficiency close to 10 % ph/el (photons per electron), corresponding to a luminance efficiency of ～ 30 cd A^–1 and a power efficiency of ～ 21 lm W^–1, is obtained by using 5 wt.‐% 1 as the guest dopant.     

Synthesis and Characterization of Red‐Emitting Iridium(III) Complexes for Solution‐Processable Phosphorescent Organic Light‐Emitting Diodes

A new series of highly efficient red‐emitting phosphorescent Ir(III) complexes, (Et‐CVz‐PhQ)₂Ir(pic‐N‐O), (Et‐CVz‐PhQ)₂Ir(pic), (Et‐CVz‐PhQ)₂Ir(acac), (EO‐CVz‐PhQ)₂Ir(pic‐N‐O), (EO‐CVz‐PhQ)₂Ir(pic), and (EO‐CVz‐PhQ)₂Ir(acac), based on carbazole (CVz)‐phenylquinoline (PhQ) main ligands and picolinic acid N‐oxide (pic‐N‐O), picolinic acid (pic), and acetylacetone (acac) ancillary ligands, are synthesized for phosphorescent organic light‐emitting diodes (PhOLEDs), and their photophysical, electrochemical, and electroluminescent (EL) properties are investigated. All of the Ir(III) complexes have high thermal stability and emit an intense red light with an excellent color purity at CIE coordinates of (0.65,0.34). Remarkably, high‐performance solution‐processable PhOLEDs were fabricated using Ir(III) complexes with a pic‐N‐O ancillary ligand with a maximum external quantum efficiency (5.53%) and luminance efficiency (8.89 cd A^?1). The novel use of pic‐N‐O ancillary ligand in the synthesis of phosphorescent materials is reported. The performance of PhOLEDs using these Ir(III) complexes correlates well with the results of density functional theory calculations.     

Efficient Organic Light‐Emitting Diodes based on Sublimable Charged Iridium Phosphorescent Emitters

The synthesis and characterization of two new phosphorescent cationic iridium(III) cyclometalated diimine complexes with formula [Ir( L )₂(N‐N)]⁺(PF₆^–) ( HL = (9,9‐diethyl‐7‐pyridinylfluoren‐2‐yl)diphenylamine); N‐N = 4,4′‐dimethyl‐2,2′‐bipyridine ( 1 ), 4,7‐dimethyl‐1,10‐phenanthroline ( 2 )) are reported. Both complexes are coordinated by cyclometalated ligands consisting of hole‐transporting diphenylamino (DPA)‐ and fluorene‐based 2‐phenylpyridine moieties. Structural information on these heteroleptic complexes has been obtained by using an X‐ray diffraction study of complex 2 . Complexes 1 and 2 are morphologically and thermally stable ionic solids and are good yellow phosphors at room temperature with relatively short lifetimes in both solution and solid phases. These robust iridium complexes can be thermally vacuum‐sublimed and used as phosphorescent dyes for the fabrication of high‐efficiency organic light‐emitting diodes (OLEDs). These devices doped with 5 wt % 1 can produce efficient electrophosphorescence with a maximum brightness of up to 15 610 cd m^–2 and a peak external quantum efficiency of ca. 7 % photons per electron that corresponds to a luminance efficiency of ca. 20 cd A^–1 and a power efficiency of ca. 19 lm W^–1. These results show that charged iridium(III) materials are useful alternative electrophosphors for use in evaporated devices in order to realize highly efficient doped OLEDs.     

Highly Efficient Red Phosphorescent OLEDs based on Non‐Conjugated Silicon‐Cored Spirobifluorene Derivative Doped with Ir‐Complexes

A novel host material containing silicon‐cored spirobifluorene derivative (SBP‐TS‐PSB), is designed, synthesized, and characterized for red phosphorescent organic light‐emitting diodes (OLEDs). The SBP‐TS‐PSB has excellent thermal and morphological stabilities and exhibits high electroluminescence (EL) efficiency as a host for the red phosphorescent OLEDs. The electrophosphorescence properties of the devices using SBP‐TS‐PSB as the host and red phosphorescent iridium (III) complexes as the emitter are investigated and these devices exhibit higher EL performances compared with the reference devices with 4,4′‐N,N′‐dicarbazole‐biphenyl (CBP) as a host material; for example, a (piq)₂Ir(acac)‐doped SBP‐TS‐PSB device shows maximum external quantum efficiency of η_ext = 14.6%, power efficiency of 10.3 lm W^?1 and Commission International de L'Eclairage color coordinates (0.68, 0.32) at J = 1.5 mA cm^?2, while the device with the CBP host shows maximum η_ext = 12.1%. These high performances can be mainly explained by efficient triplet energy transfer from the host to the guests and improved charge balance attributable to the bipolar characteristics of the spirobifluorene group.     

White‐Light‐Emitting Diodes Based on Iridium Complexes via Efficient Energy Transfer from a Conjugated Polymer

Efficient white‐light‐emitting diodes (WLEDs) have been developed using a polyfluorene‐type blue‐emitting conjugated polymer doped with green and red phosphorescent dyes. The emission spectrum of the conjugated polymer, which has a very high luminescent efficiency, shows a large spectral overlap with the absorbance of green and red iridium complexes. Also, efficient energy transfer from the conjugated polymer to the iridium complexes is observed. Poly(N‐vinyl carbazole) is used to improve the miscibility between conjugated polymer and iridium complexes because of their poor chemical compatibility and phase separation. A white emission spectrum is easily obtained by varying the contents of the three materials and controlling the phase morphology. Moreover, these WLEDs show a voltage‐independent electroluminescence owing to the threshold and driving voltage of the three materials being similar as a result of energy transfer.     

Blue‐Emitting Iridium(III) Complexes for Light‐Emitting Electrochemical Cells: Advances,Challenges, and Future Prospects

Light‐emitting electrochemical cells (LECs) are one of the most promising technologies for solid‐sate lighting. Among them, LECs based on phosphorescent iridium(III) complexes have attracted significant research interest in the past 15 years, because of their high efficiency and tunable emission color across the entire visible spectrum. To fabricate white LECs for lighting, high‐performance blue LECs are the first prerequisite. Huge efforts have been devoted to improving the performances of blue LECs based on iridium(III) complexes either by developing new blue‐emitting complexes or by engineering the devices. Nevertheless, blue LECs have still shown much lower performances (brightness, efficiency, stability, etc.) compared to the red, orange‐red, yellow, and green counterpart devices. In particular, a single blue LEC with satisfactory blue‐color purity, high efficiency, and high stability is still missing. Here, the advances in blue‐emitting iridium(III) complexes for LECs and the device engineering on LECs using the complexes are reported. The challenges ahead are discussed, and future prospects are outlined.     

A Multifunctional Iridium‐Carbazolyl Orange Phosphor for High‐Performance Two‐Element WOLED Exploiting Exciton‐Managed Fluorescence/Phosphorescence

By attaching a bulky, inductively electron‐withdrawing trifluoromethyl (CF₃) group on the pyridyl ring of the rigid 2‐[3‐ (N‐phenylcarbazolyl)]pyridine cyclometalated ligand, we successfully synthesized a new heteroleptic orange‐emitting phosphorescent iridium(III) complex [Ir( L ₁ )₂(acac)] 1 ( HL ₁ = 5‐trifluoromethyl‐2‐[3‐(N‐phenylcarbazolyl)]pyridine, Hacac = acetylacetone) in good yield. The structural and electronic properties of 1 were examined by X‐ray crystallography and time‐dependent DFT calculations. The influence of CF₃ substituents on the optical, electrochemical and electroluminescence (EL) properties of 1 were studied. We note that incorporation of the carbazolyl unit facilitates the hole‐transporting ability of the complex, and more importantly, attachment of CF₃ group provides an access to a highly efficient electrophosphor for the fabrication of orange phosphorescent organic light‐emitting diodes (OLEDs) with outstanding device performance. These orange OLEDs can produce a maximum current efficiency of ～40 cd A^?1, corresponding to an external quantum efficiency of ～12% ph/el (photons per electron) and a power efficiency of ～24 lm W^?1. Remarkably, high‐performance simple two‐element white OLEDs (WOLEDs) with excellent color stability can be fabricated using an orange triplet‐harvesting emitter 1 in conjunction with a blue singlet‐harvesting emitter. By using such a new system where the host singlet is resonant with the blue fluorophore singlet state and the host triplet is resonant with the orange phosphor triplet level, this white light‐emitting structure can achieve peak EL efficiencies of 26.6 cd A^?1 and 13.5 lm W^?1 that are generally superior to other two‐element all‐fluorophore or all‐phosphor OLED counterparts in terms of both color stability and emission efficiency.     

Facile Synthesis of Highly Efficient Lepidine‐Based Phosphorescent Iridium(III) Complexes for Yellow and White Organic Light‐Emitting Diodes

Highly efficient lepidine‐based phosphorescent iridium(III) complexes with pentane‐2,4‐dione or triazolpyridine as ancillary ligands have been designed and prepared by a newly developed facile synthetic route. Fluorine atoms and trifluoromethyl groups have been introduced into the different positions of ligand, and their influence on the photophysical properties of complexes has been investigated in detail. All the triazolpyridine‐based complexes display the blueshifted dual‐peak emission compared to the pentane‐2,4‐dione‐based ones with a broad single‐peak emission. The complexes show emission with broad full width at half maximum (FWHM) over 100 nm, and the emissions are ranges from greenish–yellow to orange region with the absolute quantum efficiency (Φ_PL) of 0.21–0.92 in solution, i.e., Φ_PL = 0.92 ( 18 ), which is the highest value among the reported neutral yellow iridium(III) complexes. Furthermore, high‐performance yellow and complementary‐color‐based white organic light‐emitting diodes (OLEDs) have been fabricated. The FWHMs of the yellow, greenish–yellow OLEDs are in the range of 94–102 nm, which are among the highest values of the reported yellow or greenish–yellow‐emitting devices without excimer emission. The maximum external quantum efficiency of monochrome OLEDs can reach 24.1%, which is also the highest value among the reported yellow or greenish–yellow devices. The color rendering indexes of blue and complementary yellow‐based white OLED is as high as 78.     

Highly efficient,orange–red organic light-emitting diodes using a series of green-emission iridium complexes as hosts

We investigated highly efficient phosphorescent organic light-emitting diodes (OLEDs) based on an orange–red emission iridium complex as the guest and five green emission iridium complexes as the host material, respectively. For comparison, a device using a common fluorescent host CBP (4,4′-bis(N-carbazolyl)-1,1′-biphenyl) has also been fabricated. Results show that the steric hindrance and exciton transporting property of the iridium complex host are found to be critical to this kind of doping system, a proper steric hindrance and improved exciton transporting ability result in reducing of triplet–triplet annihilation, thus improving of the device performance. In addition, all devices using iridium complexes as host have better performance than that of CBP, which arised from the fact that those green emission iridium complexes have a lower triplet excited energy befitting for energy confinement and a higher highest occupied molecular orbital (HOMO) level for hole injection.     

Optimization of Orange‐Emitting Electrophosphorescent Copolymers for Organic Light‐Emitting Diodes

Orange‐emitting phosphorescent copolymers containing iridium complexes and bis(carbazolyl)fluorene groups in their side chains are employed as the emissive layer in multilayer organic light‐emitting diodes (OLEDs). The efficiency of the OLED devices is optimized by varying characteristics of the copolymers: the molecular weight, the iridium loading level, and the nature and length of the linker between the side chains and the polymer backbone. A maximum efficiency of 4.9 ± 0.4%, 8.8 ± 0.7 cd A⁻¹ at 100 cd m⁻² is achieved with an optimized copolymer.     

Multifunctional Crosslinkable Iridium Complexes as Hole Transporting/Electron Blocking and Emitting Materials for Solution‐Processed Multilayer Organic Light‐Emitting Diodes

Here, a new series of crosslinkable heteroleptic iridium (III) complexes for use in solution processed phosphorescent organic light emitting diodes (OLEDs) is reported. These iridium compounds have the general formula of (PPZ‐VB)₂Ir(CˆN), where PPZ‐VB is phenylpyrazole (PPZ) vinyl benzyl (VB) ether; and the CˆN ligands represent a family of four different cyclometallating ligands including 1‐phenylpyrazolyl (PPZ) (1), 2‐(4,6‐difluorophenyl)pyridyl (DFPPY) (2), 2‐(p‐tolyl)pyridyl (TPY) (3), and 2‐phenylquinolyl (PQ) (4). With the incorporation of two crosslinkable VB ether groups, these compounds can be fully crosslinked after heating at 180 °C for 30 min. The crosslinked films exhibit excellent solvent resistance and film smoothness which enables fabrication of high‐performance multilayer OLEDs by sequential solution processing of multiple layers. Furthermore, the photophysical properties of these compounds can be easily controlled by simply changing the cyclometallating CˆN ligand in order to tune the triplet energy within the range of 3.0–2.2 eV. This diversity makes these materials not only suitable for use in hole transporting and electron blocking but also as emissive layers of several colors. Therefore, these compounds are applied as effective materials for all‐solution processed OLEDs with (PPZ‐VB)₂IrPPZ (1) acting as hole transporting and electron blocking layer and host material, as well as three other compounds, (PPZ‐VB)₂IrDFPPY ( 2 ), (PPZ‐VB)₂IrTPY(3), and (PPZ‐VB)₂IrPQ( 4 ), used as crosslinkable phosphorescent emitters.     

Efficiency Roll‐Off in Blue Emitting Phosphorescent Organic Light Emitting Diodes with Carbazole Host Materials

The efficiency roll‐off in blue phosphorescent organic light emitting diodes (OLEDs) using different carbazole compounds as the host is systematically studied. While there is no significant difference in device efficiency, OLEDs using ter‐carbazole as the host show a reduction in efficiency roll‐off at high luminance. Data from transient photoluminescence and electroluminescence measurements show that the lower triplet–triplet annihilation (TTA) and triplet–polaron quenching (TPQ) rates in devices with the ter‐carbazole host compared with other carbazole hosts are the reasons for this reduced efficiency roll‐off. It is also found that the host materials with low glass transition temperatures are more susceptible to the efficiency roll‐off problem.     

Novel Heteroleptic CuI Complexes with Tunable Emission Color for Efficient Phosphorescent Light‐Emitting Diodes

A series of orange‐red to red phosphorescent heteroleptic Cu^I complexes (the first ligand: 2,2′‐biquinoline (bq), 4,4′‐diphenyl‐2,2′‐biquinoline (dpbq) or 3,3′‐methylen‐4,4′‐diphenyl‐2,2′‐biquinoline (mdpbq); the second ligand: triphenylphosphine or bis[2‐(diphenylphosphino)phenyl]ether (DPEphos)) have been synthesized and fully characterized. With highly rigid bulky biquinoline‐type ligands, complexes [Cu(mdpbq)(PPh₃)₂](BF₄) and [Cu(mdpbq)(DPEphos)](BF₄) emit efficiently in 20 wt % PMMA films with photoluminescence quantum yield of 0.56 and 0.43 and emission maximum of 606 nm and 617 nm, respectively. By doping these complexes in poly(vinyl carbazole) (PVK) or N‐(4‐(carbazol‐9‐yl)phenyl)‐3,6‐bis(carbazol‐9‐yl) carbazole (TCCz), phosphorescent organic light‐emitting diodes (OLEDs) were fabricated with various device structures. The complex [Cu(mdpbq)(DPEphos)](BF₄) exhibits the best device performance. With the device structure of ITO/PEDOT/TCCz:[Cu(mdpbq)(DPEphos)](BF₄) (15 wt %)/TPBI/LiF/Al (III), a current efficiency up to 6.4 cd A^–1 with the Commission Internationale de L'Eclairage (CIE) coordinates of (0.61, 0.39) has been realized. To our best knowledge, this is the first report of efficient mononuclear Cu^I complexes with red emission.     

Triplet Harvesting in Hybrid White Organic Light‐Emitting Diodes

White organic light‐emitting diodes (OLEDs) are highly efficient large‐area light sources that may play an important role in solving the global energy crisis, while also opening novel design possibilities in general lighting applications. Usually, highly efficient white OLEDs are designed by combining three phosphorescent emitters for the colors blue, green, and red. However, this procedure is not ideal as it is difficult to find sufficiently stable blue phosphorescent emitters. Here, a novel approach to meet the demanding power efficiency and device stability requirements is discussed: a triplet harvesting concept for hybrid white OLED, which combines a blue fluorophor with red and green phosphors and is capable of reaching an internal quantum efficiency of 100% if a suitable blue emitter with high‐lying triplet transition is used is introduced. Additionally, this concept paves the way towards an extremely simple white OLED design, using only a single emitter layer.     

Toward Highly Efficient Solid‐State White Light‐Emitting Electrochemical Cells: Blue‐Green to Red Emitting Cationic Iridium Complexes with Imidazole‐Type Ancillary Ligands

Using imidazole‐type ancillary ligands, a new class of cationic iridium complexes ( 1 – 6 ) is prepared, and photophysical and electrochemical studies and theoretical calculations are performed. Compared with the widely used bpy (2,2′‐bipyridine)‐type ancillary ligands, imidazole‐type ancillary ligands can be prepared and modified with ease, and are capable of blueshifting the emission spectra of cationic iridium complexes. By tuning the conjugation length of the ancillary ligands, blue‐green to red emitting cationic iridium complexes are obtained. Single‐layer light‐emitting electrochemical cells (LECs) based on cationic iridium complexes show blue‐green to red electroluminescence. High efficiencies of 8.4, 18.6, and 13.2 cd A^?1 are achieved for the blue‐green‐emitting, yellow‐emitting, and orange‐emitting devices, respectively. By doping the red‐emitting complex into the blue‐green LEC, white LECs are realized, which give warm‐white light with Commission Internationale de L'Eclairage (CIE) coordinates of (0.42, 0.44) and color‐rendering indexes (CRI) of up to 81. The peak external quantum efficiency, current efficiency, and power efficiency of the white LECs reach 5.2%, 11.2 cd A^?1, and 10 lm W^?1, respectively, which are the highest for white LECs reported so far, and indicate the great potential for the use of these cationic iridium complexes in white LECs.     

Low Roll‐Off and High Efficiency Orange Organic Light Emitting Diodes with Controlled Co‐Doping of Green and Red Phosphorescent Dopants in an Exciplex Forming Co‐Host

An exciplex forming co‐host is introduced in order to fabricate orange organic light‐emitting diodes (OLEDs) with high efficiency, low driving voltage and an extremely low efficiency roll‐off, by the co‐doping of green and red emitting phosphorescence dyes in the host. The orange OLEDs achieves a low turn‐on voltage of 2.4 V, which is equivalent to the triplet energy gap of the phosphorescent‐green emitting dopant, and a very high external quantum efficiency (EQE) of 25.0%. Moreover, the OLEDs show low efficiency roll‐off with an EQE of over 21% at 10 000 cdm^?2. The device displays a very good orange color (CIE of (0.501, 0.478) at 1000 cdm^?2) with very little color shift with increasing luminance. The transient electroluminescence of the OLEDs indicate that both energy transfer and direct charge trapping takes place in the devices.     

Very High Efficiency Orange‐Red Light‐Emitting Devices with Low Roll‐Off at High Luminance Based on an Ideal Host–Guest System Consisting of Two Novel Phosphorescent Iridium Complexes with Bipolar Transport

Two phosphorescent iridium complexes with bipolar transporting ability, namely FPPCA (500 nm) and BZQPG (600 nm), are synthesized and employed as an ideal host‐guest system for phosphorescent organic light emitting diodes (PHOLEDs).The devices give very high‐efficiency orange‐red emission from BZQPG with maximum external quantum efficiency (EQE or η_ext) of >27% and maximum power efficiency (PE or η_p) of >75 lm/W, and maintain high levels of 26% and 55 lm/W, 25% and 40 lm/W at high luminance of 1000 and 5000 cd m^?2, respectively, within a range of 8–15 wt% of BZQPG. The realization of such high and stable EL performance results from the coexistence of two parallel paths: i) effective energy transfer from host (FPPCA) to guest (BZQPG) and ii) direct exciton formation on the BZQPG emitter, which can alternately dominate the electrophosphorescent emission. This all‐phosphor doping system removes the charge‐injection barrier from the charge‐transport process to the emissive layer (EML) due to the inherent narrow E_g of both phosphors. Therefore, this ideal host–guest system represents a new design to produce PHOLEDs with high efficiency and low efficiency roll‐off using a simple device configuration.     

Manipulating Charge‐Transfer Character with Electron‐Withdrawing Main‐Group Moieties for the Color Tuning of Iridium Electrophosphors

A new and synthetically versatile strategy has been developed for the phosphorescence color tuning of cyclometalated iridium phosphors by simple tailoring of the phenyl ring of ppy (Hppy = 2‐phenylpyridine) with various main‐group moieties in [Ir(ppy‐X)₂(acac)] (X = B(Mes)₂, SiPh₃, GePh₃, NPh₂, POPh₂, OPh, SPh, SO₂Ph). This can be achieved by shifting the charge‐transfer character from the pyridyl groups in some traditional iridium ppy‐type complexes to the electron‐withdrawing main‐group moieties and these assignments were supported by theoretical calculations. This new color tuning strategy in Ir^III‐based triplet emitters using electron‐withdrawing main‐group moieties provides access to Ir^III phosphors with improved electron injection/electron transporting features essential for highly efficient, color‐switchable organic light‐emitting diodes (OLEDs). The present work furnished OLED colors spanning from bluish‐green to red (505–609 nm) with high electroluminescence efficiencies which have great potential for application in multicolor displays. The maximum external quantum efficiency of 9.4%, luminance efficiency of 10.3 cd A⁻¹ and power efficiency of 5.0 lm W⁻¹ for the red OLED (X = B(Mes)₂), 11.1%, 35.0 cd A⁻¹, and 26.8 lm W⁻¹ for the bluish‐green device (X = OPh), 10.3%, 36.9 cd A⁻¹, and 28.6 lm W⁻¹ for the bright green device (X = NPh₂) as well as 10.7%, 35.1 cd A⁻¹, and 23.1 lm W⁻¹ for the yellow‐emitting device (X = SO₂Ph) can be obtained.