Novel Dy3+-doped Gd(PO3)3 white light phosphors each with an orthorhombic system are successfully synthesized by solid-state reaction.The luminescence properties of white-light Gd1-x(PO3)3:xDy3+(0 < x ≤ 0.25) unde...Novel Dy3+-doped Gd(PO3)3 white light phosphors each with an orthorhombic system are successfully synthesized by solid-state reaction.The luminescence properties of white-light Gd1-x(PO3)3:xDy3+(0 < x ≤ 0.25) under vacuum ultraviolet(VUV) excitation are investigated.The strong absorption at around 147 nm in excitation spectrum energy can be transferred to the energy levels of Dy3+ ion from the host absorption.Additionally,the white light phosphor is activated by a single Dy3+ ion.Therefore,the luminescence of Gd1-x(PO3)3:xDy(0 < x ≤ 0.25) under VUV excitation is effective,and it has the promise of being applied to mercury-free lamps.展开更多
As an improvement of reported Y2O2S:Tb3+, a white-light long-lasting phosphor: Y2O2S:Tb3+, Sm3+ was prepared by the solid-state reaction. The photo-luminescence spectra showed that the position and shape of Tb3+ and S...As an improvement of reported Y2O2S:Tb3+, a white-light long-lasting phosphor: Y2O2S:Tb3+, Sm3+ was prepared by the solid-state reaction. The photo-luminescence spectra showed that the position and shape of Tb3+ and Sm3+ emissions under UV excitation were similar in this host, which ensured a stable white emission color (daylight standard of IEC) under different excitations. The decay curves of co-doped samples indicated that the decay times of emissions of the two ions were close. The thermo-luminescence measurement suggested that the traps created by the doped Sm3+ ions were helpful to postpone the white afterglow of co-doped samples. Therefore, the function of co-doped Sm3+ ions was confirmed as improving the white emission colors of samples and acting as new trap centers.展开更多
A novel white light emitting long-lasting phosphor Cd1-xDyxSiO3 is reported in this letter. The Dy3+ doped CdSiO3 phosphor emits white light. The phosphorescence can be seen with the naked eye in the dark clearly even...A novel white light emitting long-lasting phosphor Cd1-xDyxSiO3 is reported in this letter. The Dy3+ doped CdSiO3 phosphor emits white light. The phosphorescence can be seen with the naked eye in the dark clearly even after the 254 nm UV irradiation have been removed for about 30 min. In the emission spectrum of 5% Dy3+ doped CdSiO3 phosphor, there are two emission peaks of Dy3+, 580 nm (4F9/26H13/2) and 486 nm (4F9/26H15/2), as well as a broad band emission located at about 410 nm. All the three emissions form a white light with CIE chromaticity coordinates x=0.3874, y=0.3760 and the color temperature is 4000 K under 254 nm excitation. It indicated that this phosphor is a promising new luminescent material for practice application.展开更多
A white long-lasting phosphor Ca2MgSi2O7:Dy3+ was prepared by the solid-state reaction. A strong band peaked at 260 nm was shown in the excitation spectrum of 578 nm emission, which might be attributed to the oxygen d...A white long-lasting phosphor Ca2MgSi2O7:Dy3+ was prepared by the solid-state reaction. A strong band peaked at 260 nm was shown in the excitation spectrum of 578 nm emission, which might be attributed to the oxygen deficiency of the host. After irradiated with 254 nm for 4 min, the white afterglow of the sample could be seen for 3 h. Moreover, the depths and frequency factors of trap centers were calculated from the thermo-luminescence curve of the sample, which indicated that the trap centers corresponding to the 414 K band were more helpful to the long-lasting phosphorescence.展开更多
Most of the commercial white LED lamps use blue chip coated with yellow emitting phosphor. YAG:Ce3+ phosphor is coated on blue chip to obtain white light. Though this is commercially successful, there are several draw...Most of the commercial white LED lamps use blue chip coated with yellow emitting phosphor. YAG:Ce3+ phosphor is coated on blue chip to obtain white light. Though this is commercially successful, there are several drawbacks such as “halo effect”, poor colour rendition, etc. In recent years several efforts have been made to improve LED lamp performance. In this paper modifica-tion of YAG:Ce phosphor for improving CRI, by introducing Gd3+, Pr3+ or Tb3+ at Ce3+ site is reported.展开更多
The multiple color-matching schemes that could improve the color rendering index for phosphor-free white LEDs are discussed.Then we review a few of the recent research directions for phosphor-free white LEDs,which inc...The multiple color-matching schemes that could improve the color rendering index for phosphor-free white LEDs are discussed.Then we review a few of the recent research directions for phosphor-free white LEDs,which include the development of monolithic GaN-based white LEDs and hybrid integrated GaN-based and Al Ga In P-based white LEDs.These development paths will pave the way toward commercial application of phosphor-free white LEDs in the coming years.展开更多
We report a unique red light-emitting Eu-doped borosilicate glass to convert color for warm white light-emitting diodes. This glass can be excited from 394 nm-peaked near ultraviolet light, 466 nm-peaked blue light, t...We report a unique red light-emitting Eu-doped borosilicate glass to convert color for warm white light-emitting diodes. This glass can be excited from 394 nm-peaked near ultraviolet light, 466 nm-peaked blue light, to 534 nm-peaked green light to emit the desired red light with an excellent transmission in the wavelength range of 400-700 nm which makes this glass suitable for color conversion without a great cost of luminous power loss. In particular, when assembling this glass for commercial white light-emitting diodes, the tested results show that the color rendering index is improved to 84 with a loss of luminous power by 12 percent at average, making this variety of glass promising for inorganic "remote-phosphor" color conversion.展开更多
A new convenient calcium cyanamide (CaCN2) reduction route was developed to synthesize the Eu2+ activated Ca-α-SiAlON phosphors containing low oxygen content. The luminescence properties of the obtained products were...A new convenient calcium cyanamide (CaCN2) reduction route was developed to synthesize the Eu2+ activated Ca-α-SiAlON phosphors containing low oxygen content. The luminescence properties of the obtained products were investigated for white LEDs applica- tion. The critical Eu2+ concentration in various hosts and its effect on the photoluminescence properties were studied. The optimized sample (10at.% Eu2+ vs. Ca2+) could be efficiently excited by the current GaN/InGaN blue LED chips and provided emission intensity competitive with that of YAG:Ce3+ (P46-Y3) standard, revealing that this phosphor was a potential candidate for phosphor-converted white LEDs.展开更多
Spherical YAG∶Ce3+ phosphor particles with narrow size distribution were prepared by spray pyrolysis. The effects of the concentration of solution, the flow rate of carrier gas and the annealing temperature on the ph...Spherical YAG∶Ce3+ phosphor particles with narrow size distribution were prepared by spray pyrolysis. The effects of the concentration of solution, the flow rate of carrier gas and the annealing temperature on the phosphor morphology were studied. The productivity of precursor particles shows a trend of drop after rising with the increase of concentration. Raising the flow rate of nitrogen can improve the productivity of the precursor particles. Phosphor prepared by spray pyrolysis has obviously higher emission intensity than that synthesized by solid state reaction, spray pyrolysis makes Ce3+ ions well distributed in the crystal lattice as the luminescent centers, and phosphor particles have regular sphericity and narrow size distribution.展开更多
Ce3+-activated yttrium aluminum garnet (YAG) was prepared by the solid-state reaction, in which H3BO3, LiF, NaF, KF and BaF2 were used as the fluxes. The effect of fluxes on optical properties of phosphors was studied...Ce3+-activated yttrium aluminum garnet (YAG) was prepared by the solid-state reaction, in which H3BO3, LiF, NaF, KF and BaF2 were used as the fluxes. The effect of fluxes on optical properties of phosphors was studied in detail, especially the fluxes of alkali fluorides, which could enhance the emission intensity and change the wavelength of emission peaks. Among these YAG:Ce phosphors, the phosphor sintered with H3BO3 and NaF exhibited the strongest emission. The emission peaks of phosphors prepared with fluxes from LiF to KF were shifted to long wavelength. The effect of NaF concentration on the emission intensity of YAG:Ce was also investigated. The value of emission intensity reached the maximum when the concentration of NaF was 0.5%.展开更多
Eu3+-doped Gd2Mo3O9 was prepared by solid-state reaction method using Na2CO3 as flux and characterized by powder X-ray diffractometry. According to X-ray diffraction, this material belonged to a tetragonal system with...Eu3+-doped Gd2Mo3O9 was prepared by solid-state reaction method using Na2CO3 as flux and characterized by powder X-ray diffractometry. According to X-ray diffraction, this material belonged to a tetragonal system with space group I41/a. The effects of flux content and sintering temperature on the luminescent properties were investigated with the emission and excitation spectra. The results showed that flux content and sintering temperature had effects on the luminescent properties, the optimized flux content and the best temperature was 3% and 800 ℃, respectively. The excitation and emission spectra also showed that this phosphor could be effectively excited by C-T band (280 nm), ultraviolet light 395 nm and blue light 465 nm. The wavelengths at 395 and 465 nm were nicely fitting in with the widely applied output wavelengths of ultraviolet or blue LED chips. Integrated emission intensity of Gd2Mo3O9∶Eu was twice higher than that of Y2O2S∶Eu3+ under 395 nm excitation. The Eu3+ doped Gd2Mo3O9 phosphor may be a better candidate in solid-state lighting applications.展开更多
A series of YAG:Ce,Tb phosphors were synthesized by vacuum sintering method.Moreover,their spectral properties,thermal quenching behaviors and color rendering properties were investigated systematically.The photolumin...A series of YAG:Ce,Tb phosphors were synthesized by vacuum sintering method.Moreover,their spectral properties,thermal quenching behaviors and color rendering properties were investigated systematically.The photoluminescence emission spectra of YAG:Ce,Tb show a great red shift compared with that of YAG:Ce.Direct energy transfer from Tb^(3+) to Ce^(3+) ions is verified based on the analysis of different photoluminescence spectra.The quenching temperature for Tb^(3+)-doped YAG:Ce phosphors is about 490 K.The thermal activation energy is estimated to be 0.18 and 0.291 eV for Tb^(3+)-doped YAG:Ce and YAG:Ce phosphors,respectively.The smaller activation energy for Tb^(3+)-doped YAG:Ce means a more rapid nonradiative transition from 5d to 4f state,thus resulting in the lower quenching temperature.In addition,white LEDs with improved color rendering properties are achieved by using modified YAG:Ce,Tb phosphors.展开更多
In order to prepare fluorescent material for white Light Emitting Diodes (LEDs), a new Eu3+ activated molybdate phosphor SrMoO4 was fabricated with solid-state method. X-ray diffraction (XRD) showed that the doping of...In order to prepare fluorescent material for white Light Emitting Diodes (LEDs), a new Eu3+ activated molybdate phosphor SrMoO4 was fabricated with solid-state method. X-ray diffraction (XRD) showed that the doping of trivalent europium ion reduced the lattice parameters. The excitation and emission spectra indicated that this phosphor could be excited effectively by the visible light, and then emitted red light with the peaks located at 616 and 624 nm. The influence of Eu3+ concentration on the luminescent properties of Eu3+ doped SrMoO4 was investigated and the 25%(mole fraction) was the appropriate molar concentration. The reaction time and temperature had obvious effect on the luminescent properties. The luminescent intensity reached the strongest when it was sintered at 800 ℃ for 3 h.展开更多
As the blue and yellow lights are complementary colors, a blue InGaN LED chip is coated by a yellow phosphor film to generate white light based on luminescence conversion mechanism. The emitted light of a blue LED is ...As the blue and yellow lights are complementary colors, a blue InGaN LED chip is coated by a yellow phosphor film to generate white light based on luminescence conversion mechanism. The emitted light of a blue LED is used as the primary source for exciting fluorescent material such as cerium doped yttrium aluminum garnet with the formula Y3Al5O12∶Ce3+(in short: YAG∶Ce3+). The matching of the spectrum of the blue LED chips and the YAG∶Ce3+ yellow phosphor is studied to improve the conversion efficiency. The packaging methods and manufacturing processes for high-power single-chip-white-LEDs are introduced. The uniformity of the output white light is investigated. Based on the characteristics of the high-power white LEDs, some approaches and processes are suggested to improve the light uniformity when they are fabricated. The effectiveness of those approaches on the improvement of LEDs is discussed in detail and some interesting conclusions are also presented.展开更多
An efficient color-tunable hybrid white organic light-emitting diode is demonstrated with double interlayers of 2,7-bis(carbazol-9-yl)-9,9-ditoylfluo- rene/2-(diphenylphosphoryl) spiroflu-orene (DMFL-CBP/SPPO1) insert...An efficient color-tunable hybrid white organic light-emitting diode is demonstrated with double interlayers of 2,7-bis(carbazol-9-yl)-9,9-ditoylfluo- rene/2-(diphenylphosphoryl) spiroflu-orene (DMFL-CBP/SPPO1) inserted between blue fluorescent and yellow phosphorescent-emitting layers, and exhibits Commission Internationale de l’Eclairage (CIE1931) ranging from warm white (0.4368, 0.4497) to cool white (0.2781, 0.2896) with driving current density from 0.2 to 40 mA/cm2. The recombination of singlet and the triplet excitons in blue fluores-cent-emitting layer and yellow phosphorescent-emitting layer, respectively, can be modulated by both the thickness of these double interlayers and the applied current densities.展开更多
基金Project supported by the National Natural Science Foundation for Young Scientists of China (Grant No. 502041032)
文摘Novel Dy3+-doped Gd(PO3)3 white light phosphors each with an orthorhombic system are successfully synthesized by solid-state reaction.The luminescence properties of white-light Gd1-x(PO3)3:xDy3+(0 < x ≤ 0.25) under vacuum ultraviolet(VUV) excitation are investigated.The strong absorption at around 147 nm in excitation spectrum energy can be transferred to the energy levels of Dy3+ ion from the host absorption.Additionally,the white light phosphor is activated by a single Dy3+ ion.Therefore,the luminescence of Gd1-x(PO3)3:xDy(0 < x ≤ 0.25) under VUV excitation is effective,and it has the promise of being applied to mercury-free lamps.
基金the National Natural Science Foundation of China (10404028)Young Scientists Innovation Foundation of Fujian Province (2007F3027)
文摘As an improvement of reported Y2O2S:Tb3+, a white-light long-lasting phosphor: Y2O2S:Tb3+, Sm3+ was prepared by the solid-state reaction. The photo-luminescence spectra showed that the position and shape of Tb3+ and Sm3+ emissions under UV excitation were similar in this host, which ensured a stable white emission color (daylight standard of IEC) under different excitations. The decay curves of co-doped samples indicated that the decay times of emissions of the two ions were close. The thermo-luminescence measurement suggested that the traps created by the doped Sm3+ ions were helpful to postpone the white afterglow of co-doped samples. Therefore, the function of co-doped Sm3+ ions was confirmed as improving the white emission colors of samples and acting as new trap centers.
文摘A novel white light emitting long-lasting phosphor Cd1-xDyxSiO3 is reported in this letter. The Dy3+ doped CdSiO3 phosphor emits white light. The phosphorescence can be seen with the naked eye in the dark clearly even after the 254 nm UV irradiation have been removed for about 30 min. In the emission spectrum of 5% Dy3+ doped CdSiO3 phosphor, there are two emission peaks of Dy3+, 580 nm (4F9/26H13/2) and 486 nm (4F9/26H15/2), as well as a broad band emission located at about 410 nm. All the three emissions form a white light with CIE chromaticity coordinates x=0.3874, y=0.3760 and the color temperature is 4000 K under 254 nm excitation. It indicated that this phosphor is a promising new luminescent material for practice application.
基金Project supported by the Young Scientists' Innovation Foundation of Fujian Province (2007F3027)the Natural Science Foundation of Fujian Province of China (A0510014)+2 种基金the Science Foundation of the Department of Science and Technology of Fujian Province of China (2006F5025)the Science Foundation of the Educational Department of Fujian Province of China (JB08063)the Special Science Foundation for Key Research of Fujian Province (2007HJ0004-2)
文摘A white long-lasting phosphor Ca2MgSi2O7:Dy3+ was prepared by the solid-state reaction. A strong band peaked at 260 nm was shown in the excitation spectrum of 578 nm emission, which might be attributed to the oxygen deficiency of the host. After irradiated with 254 nm for 4 min, the white afterglow of the sample could be seen for 3 h. Moreover, the depths and frequency factors of trap centers were calculated from the thermo-luminescence curve of the sample, which indicated that the trap centers corresponding to the 414 K band were more helpful to the long-lasting phosphorescence.
文摘Most of the commercial white LED lamps use blue chip coated with yellow emitting phosphor. YAG:Ce3+ phosphor is coated on blue chip to obtain white light. Though this is commercially successful, there are several drawbacks such as “halo effect”, poor colour rendition, etc. In recent years several efforts have been made to improve LED lamp performance. In this paper modifica-tion of YAG:Ce phosphor for improving CRI, by introducing Gd3+, Pr3+ or Tb3+ at Ce3+ site is reported.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61222501 and 61335004)the Specialized Research Fund for the Doctoral Program of Higher Education of China(Grant No.20111103110019)
文摘The multiple color-matching schemes that could improve the color rendering index for phosphor-free white LEDs are discussed.Then we review a few of the recent research directions for phosphor-free white LEDs,which include the development of monolithic GaN-based white LEDs and hybrid integrated GaN-based and Al Ga In P-based white LEDs.These development paths will pave the way toward commercial application of phosphor-free white LEDs in the coming years.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 50872091 and 21076161)the Tianjin Municipal Sci/Tech. Commission, China (Grant Nos. 10SYSYJC28100 and 2006ZD30)the Tianjin Municipal Higher Education Commission, China (Grant No. 20110304)
文摘We report a unique red light-emitting Eu-doped borosilicate glass to convert color for warm white light-emitting diodes. This glass can be excited from 394 nm-peaked near ultraviolet light, 466 nm-peaked blue light, to 534 nm-peaked green light to emit the desired red light with an excellent transmission in the wavelength range of 400-700 nm which makes this glass suitable for color conversion without a great cost of luminous power loss. In particular, when assembling this glass for commercial white light-emitting diodes, the tested results show that the color rendering index is improved to 84 with a loss of luminous power by 12 percent at average, making this variety of glass promising for inorganic "remote-phosphor" color conversion.
基金a Grant-in-Aid for the Scientific Research (No16080210) on Priority Areas (440) from the Ministry of Education, Culture, Sports, Science and Technology of Japan
文摘A new convenient calcium cyanamide (CaCN2) reduction route was developed to synthesize the Eu2+ activated Ca-α-SiAlON phosphors containing low oxygen content. The luminescence properties of the obtained products were investigated for white LEDs applica- tion. The critical Eu2+ concentration in various hosts and its effect on the photoluminescence properties were studied. The optimized sample (10at.% Eu2+ vs. Ca2+) could be efficiently excited by the current GaN/InGaN blue LED chips and provided emission intensity competitive with that of YAG:Ce3+ (P46-Y3) standard, revealing that this phosphor was a potential candidate for phosphor-converted white LEDs.
基金Project supported by National "The Tenth Five-Year"plan (2003BA316A01-03-05) and "The Tenth Five-Year"Plan(BE2004021) of Jiangsu provicce
文摘Spherical YAG∶Ce3+ phosphor particles with narrow size distribution were prepared by spray pyrolysis. The effects of the concentration of solution, the flow rate of carrier gas and the annealing temperature on the phosphor morphology were studied. The productivity of precursor particles shows a trend of drop after rising with the increase of concentration. Raising the flow rate of nitrogen can improve the productivity of the precursor particles. Phosphor prepared by spray pyrolysis has obviously higher emission intensity than that synthesized by solid state reaction, spray pyrolysis makes Ce3+ ions well distributed in the crystal lattice as the luminescent centers, and phosphor particles have regular sphericity and narrow size distribution.
基金supported by the Science Technology Project of Zhejiang Province (2008C21153)the National Natural Science Foundation of China (60508014 and 50772102)+1 种基金Program for New Century Excellent Talents in University (NCET-07-0786)the Nature Science Foundation of Zhejiang Province (R406007)
文摘Ce3+-activated yttrium aluminum garnet (YAG) was prepared by the solid-state reaction, in which H3BO3, LiF, NaF, KF and BaF2 were used as the fluxes. The effect of fluxes on optical properties of phosphors was studied in detail, especially the fluxes of alkali fluorides, which could enhance the emission intensity and change the wavelength of emission peaks. Among these YAG:Ce phosphors, the phosphor sintered with H3BO3 and NaF exhibited the strongest emission. The emission peaks of phosphors prepared with fluxes from LiF to KF were shifted to long wavelength. The effect of NaF concentration on the emission intensity of YAG:Ce was also investigated. The value of emission intensity reached the maximum when the concentration of NaF was 0.5%.
基金Project supported by the National Natural Science Foundation of China (50572102, 50502031) Natural Science Foundation of Jilin Province (1999514, 2003051422) Outstanding Young People Foundation of Jilin Province (20040113)
文摘Eu3+-doped Gd2Mo3O9 was prepared by solid-state reaction method using Na2CO3 as flux and characterized by powder X-ray diffractometry. According to X-ray diffraction, this material belonged to a tetragonal system with space group I41/a. The effects of flux content and sintering temperature on the luminescent properties were investigated with the emission and excitation spectra. The results showed that flux content and sintering temperature had effects on the luminescent properties, the optimized flux content and the best temperature was 3% and 800 ℃, respectively. The excitation and emission spectra also showed that this phosphor could be effectively excited by C-T band (280 nm), ultraviolet light 395 nm and blue light 465 nm. The wavelengths at 395 and 465 nm were nicely fitting in with the widely applied output wavelengths of ultraviolet or blue LED chips. Integrated emission intensity of Gd2Mo3O9∶Eu was twice higher than that of Y2O2S∶Eu3+ under 395 nm excitation. The Eu3+ doped Gd2Mo3O9 phosphor may be a better candidate in solid-state lighting applications.
基金supported by the National Natural Science Foundation of China(51272282,51302311)the Beijing Committee of Science and Technology(Z13111000280000)the Education Commission of Beijing(2011010329)
文摘A series of YAG:Ce,Tb phosphors were synthesized by vacuum sintering method.Moreover,their spectral properties,thermal quenching behaviors and color rendering properties were investigated systematically.The photoluminescence emission spectra of YAG:Ce,Tb show a great red shift compared with that of YAG:Ce.Direct energy transfer from Tb^(3+) to Ce^(3+) ions is verified based on the analysis of different photoluminescence spectra.The quenching temperature for Tb^(3+)-doped YAG:Ce phosphors is about 490 K.The thermal activation energy is estimated to be 0.18 and 0.291 eV for Tb^(3+)-doped YAG:Ce and YAG:Ce phosphors,respectively.The smaller activation energy for Tb^(3+)-doped YAG:Ce means a more rapid nonradiative transition from 5d to 4f state,thus resulting in the lower quenching temperature.In addition,white LEDs with improved color rendering properties are achieved by using modified YAG:Ce,Tb phosphors.
基金Project supported by the Hebei Developing Foundation of Science &Technology (51215103b)
文摘In order to prepare fluorescent material for white Light Emitting Diodes (LEDs), a new Eu3+ activated molybdate phosphor SrMoO4 was fabricated with solid-state method. X-ray diffraction (XRD) showed that the doping of trivalent europium ion reduced the lattice parameters. The excitation and emission spectra indicated that this phosphor could be excited effectively by the visible light, and then emitted red light with the peaks located at 616 and 624 nm. The influence of Eu3+ concentration on the luminescent properties of Eu3+ doped SrMoO4 was investigated and the 25%(mole fraction) was the appropriate molar concentration. The reaction time and temperature had obvious effect on the luminescent properties. The luminescent intensity reached the strongest when it was sintered at 800 ℃ for 3 h.
基金"863"Project from Ministry of Science & Technology of China(2006AA03A116)
文摘As the blue and yellow lights are complementary colors, a blue InGaN LED chip is coated by a yellow phosphor film to generate white light based on luminescence conversion mechanism. The emitted light of a blue LED is used as the primary source for exciting fluorescent material such as cerium doped yttrium aluminum garnet with the formula Y3Al5O12∶Ce3+(in short: YAG∶Ce3+). The matching of the spectrum of the blue LED chips and the YAG∶Ce3+ yellow phosphor is studied to improve the conversion efficiency. The packaging methods and manufacturing processes for high-power single-chip-white-LEDs are introduced. The uniformity of the output white light is investigated. Based on the characteristics of the high-power white LEDs, some approaches and processes are suggested to improve the light uniformity when they are fabricated. The effectiveness of those approaches on the improvement of LEDs is discussed in detail and some interesting conclusions are also presented.
文摘An efficient color-tunable hybrid white organic light-emitting diode is demonstrated with double interlayers of 2,7-bis(carbazol-9-yl)-9,9-ditoylfluo- rene/2-(diphenylphosphoryl) spiroflu-orene (DMFL-CBP/SPPO1) inserted between blue fluorescent and yellow phosphorescent-emitting layers, and exhibits Commission Internationale de l’Eclairage (CIE1931) ranging from warm white (0.4368, 0.4497) to cool white (0.2781, 0.2896) with driving current density from 0.2 to 40 mA/cm2. The recombination of singlet and the triplet excitons in blue fluores-cent-emitting layer and yellow phosphorescent-emitting layer, respectively, can be modulated by both the thickness of these double interlayers and the applied current densities.
