The photoluminescence(PL)peak of poly p-phenyl phenol(PPP)is at about 370-420nm excited by the light at 350nm.The absorption band edges and photon emitting peaks of the polymer are found the conjugated lengths depende...The photoluminescence(PL)peak of poly p-phenyl phenol(PPP)is at about 370-420nm excited by the light at 350nm.The absorption band edges and photon emitting peaks of the polymer are found the conjugated lengths dependent on molecular weight of polymer.In the transient luminescence measurement the lifetime of PL decay is determined to be 2.0ns which is supposed an evidence of polaron excitation recombination.The electroluminescence is observed with aluminum/PPP/indium-tinoxide cell.展开更多
The polymer electroluminescence (EL) device with PBD as carriers confinement layer yields bright blue emission having intensity of 300cd/m^(2),in same case the device without PBD layer have luminance only 44 cd/m^(2)....The polymer electroluminescence (EL) device with PBD as carriers confinement layer yields bright blue emission having intensity of 300cd/m^(2),in same case the device without PBD layer have luminance only 44 cd/m^(2).The effect of PBD layer on EL characteristic was studied.The results show that only in EL devices with PBD thick-ness over 30nm,the holes are completely confined in emitting layer.The luminance over 2000cd/m^(2) can be obtained by inserting an electron injecting layer between the negative electrode and PED to increase the electron injection.展开更多
By placing a hole blocking layer between the polymer and the metallic electrode,we have achieved improved efficiencies for blue electroluminescent devices fabricated with poly(N-vinylcarbazole)doped with 1,1,4,4,-tetr...By placing a hole blocking layer between the polymer and the metallic electrode,we have achieved improved efficiencies for blue electroluminescent devices fabricated with poly(N-vinylcarbazole)doped with 1,1,4,4,-tetraphenyl-1,3-butadiene as the emitter layer and with aluminum and indium/tin-oxide as the electron and hole injecting electrodes.This bilayer device yields bright blue emission having intensity of 300cd/m^(2),in same case the devices without hole blocking layer have luminance of only 44 cd/m^(2).展开更多
Blue-green electroluminescent diodes utilizing tris(8-Quinolino1ato)-aluminum doped poly(vinylcarbazole)have been demonstrated.A Schottky-type electroluminescent diode of the polymer film is driven at 20V and has a pe...Blue-green electroluminescent diodes utilizing tris(8-Quinolino1ato)-aluminum doped poly(vinylcarbazole)have been demonstrated.A Schottky-type electroluminescent diode of the polymer film is driven at 20V and has a peak emission wavelength of 490nm at room temperature with lifetime up to 4 h.展开更多
Exciton(or spin)statistics is a physical principle based on the statistics of spin multiplicity.In electroluminescence,injected electrons and holes have randomized spin states,and usually form singlet or triplet excit...Exciton(or spin)statistics is a physical principle based on the statistics of spin multiplicity.In electroluminescence,injected electrons and holes have randomized spin states,and usually form singlet or triplet excitons in the ratio of 1:3.Exciton statistics determines that the upper limit of internal quantum efficiency is 25%in fluorescent devices,since only singlet exciton can decay radiatively.However,both experimental and theoretical evidence indicate that the actual efficiency can exceed the exciton statistics limit of 25%by utilizing materials with special electronic structure and optimized device structures.These results bring light to break through the exciton statistics limit and develop new-generation fluorescent materials with low cost and high efficiency.Recently,the exciton statistics,which has attracted great attention in the past decade,is being rejuvenated due to the discovery of some fluorescent materials with abnormally high efficiencies.In view of their significance in theoretical research of organic semiconductors and developing new-generation OLED materials,such materials are widely investigated in both academic institutions and industry.Several key issues still require further clarification for this kind of materials,such as the molecular design concepts.Herein,we review the progress of the materials with efficiency exceeding the exciton statistics limit,and the routes to improve exciton utilization efficiency.In the end,we present an innovative pathway to fully harvest the excitons in fluorescent devices,namely,"hot exciton"model and relevant fluorescence material with hybridized local and charge-transfer(HLCT)excited state.展开更多
文摘The photoluminescence(PL)peak of poly p-phenyl phenol(PPP)is at about 370-420nm excited by the light at 350nm.The absorption band edges and photon emitting peaks of the polymer are found the conjugated lengths dependent on molecular weight of polymer.In the transient luminescence measurement the lifetime of PL decay is determined to be 2.0ns which is supposed an evidence of polaron excitation recombination.The electroluminescence is observed with aluminum/PPP/indium-tinoxide cell.
基金Supported by the National Natural Science Foundation of Chinaby Key Research Projection from the National Laboratory of Integrated Optical Electronics of Jilin University
文摘The polymer electroluminescence (EL) device with PBD as carriers confinement layer yields bright blue emission having intensity of 300cd/m^(2),in same case the device without PBD layer have luminance only 44 cd/m^(2).The effect of PBD layer on EL characteristic was studied.The results show that only in EL devices with PBD thick-ness over 30nm,the holes are completely confined in emitting layer.The luminance over 2000cd/m^(2) can be obtained by inserting an electron injecting layer between the negative electrode and PED to increase the electron injection.
文摘By placing a hole blocking layer between the polymer and the metallic electrode,we have achieved improved efficiencies for blue electroluminescent devices fabricated with poly(N-vinylcarbazole)doped with 1,1,4,4,-tetraphenyl-1,3-butadiene as the emitter layer and with aluminum and indium/tin-oxide as the electron and hole injecting electrodes.This bilayer device yields bright blue emission having intensity of 300cd/m^(2),in same case the devices without hole blocking layer have luminance of only 44 cd/m^(2).
文摘Blue-green electroluminescent diodes utilizing tris(8-Quinolino1ato)-aluminum doped poly(vinylcarbazole)have been demonstrated.A Schottky-type electroluminescent diode of the polymer film is driven at 20V and has a peak emission wavelength of 490nm at room temperature with lifetime up to 4 h.
基金financially supported by the National Science Foundation of China(51073069,51273078)the National Basic Research Program of China(2013CB834801)
文摘Exciton(or spin)statistics is a physical principle based on the statistics of spin multiplicity.In electroluminescence,injected electrons and holes have randomized spin states,and usually form singlet or triplet excitons in the ratio of 1:3.Exciton statistics determines that the upper limit of internal quantum efficiency is 25%in fluorescent devices,since only singlet exciton can decay radiatively.However,both experimental and theoretical evidence indicate that the actual efficiency can exceed the exciton statistics limit of 25%by utilizing materials with special electronic structure and optimized device structures.These results bring light to break through the exciton statistics limit and develop new-generation fluorescent materials with low cost and high efficiency.Recently,the exciton statistics,which has attracted great attention in the past decade,is being rejuvenated due to the discovery of some fluorescent materials with abnormally high efficiencies.In view of their significance in theoretical research of organic semiconductors and developing new-generation OLED materials,such materials are widely investigated in both academic institutions and industry.Several key issues still require further clarification for this kind of materials,such as the molecular design concepts.Herein,we review the progress of the materials with efficiency exceeding the exciton statistics limit,and the routes to improve exciton utilization efficiency.In the end,we present an innovative pathway to fully harvest the excitons in fluorescent devices,namely,"hot exciton"model and relevant fluorescence material with hybridized local and charge-transfer(HLCT)excited state.
