高效率磷光与荧光相结合的白色有机发光器件

制作了一种白色有机电致发光器件(WOLED)。将红光[Ir(piq)2(acac)]及绿光[Ir(ppy)3]磷光掺杂染料分别掺入到母体CBP中,在2种磷光发光层间插入蓝光材料DPVBi,引入电子传输能力强的BPhen作为电子注入层和空穴阻挡层,通过改变蓝光发光层的厚度,得到了高效率的WOLED,最大电流效率可达17.6cd/A,最大功率效率达13.7lm/W,最大亮度达27525cd/m2,当电压从4V变化到12V时,色坐标从(0.54,0.35)变化到(0.30,0.31),基本处于白光区。器件的特点在于DPVBi的存在阻挡了2种磷光材料间的能量转移,色度可以通过简单地调整DPVBi的厚度,避免使用稀有的蓝光磷光材料和与其相匹配的母体材料,同时又可以保持较高的发光效率。     

锌金属配合物BFHQZn的白色有机电致发光器件

利用新型荧光染料2-溴-4-氟苯乙烯-8-羟基喹啉锌(BFHQZn,(E)-2-(2-bromo-4-fluorostyryl)quinolato-Zinc)的电致发光(EL)特性,制备了非掺杂型的有机电致白光器件(WOLED)。器件的结构为ITO/CuPc(10nm)/NPBX(25 nm)/BFHQZn(18 nm)/NPBX(xnm)/BCP(10 nm)/Alq3((47-x)nm)/LiF(0.5 nm)/Al,当x为12时,得到了色度最好和效率最大的WOLED,最大电流效率为1.11 cd/A(at 10 V),最大的亮度为817 cd/m2(at 15 V),当驱动电压从7 V(启亮)升高到15 V(最高亮度)时,器件色坐标由(0.32,038)改变为(0.30,0.28)。     

具有不同掺杂层厚度的荧光与磷光材料相结合的高效白色有机发光器件

实验制作一种多层白色有机发光器件(WOLED)。将 绿光磷光材料和红光磷光材料 Ir(piq)₂(acac)共掺到母体BPhen中作为绿光和红光发光层;荧光材料DPVBi作为蓝光发 光层,通过改变掺杂层的厚度,得到了高效率的白色WOLED。器件的最大电流效 率可达4.55cd/ A,14 V时亮度达8489cd/m² ;当电压从4V变化到12 V时,色坐标从(0.52,0.34)变化到(0.34, 0.26),基本处于白光区。此器件的 特点,在于其性能可以通过简单地调整掺杂层的厚度来控制。     

加入电子阻挡层的黄色磷光有机电致发光器件

使用绿色磷光材料GIr1和红色磷光材料R-4B作 为掺杂剂,制备了一种黄色磷光有机电致发光 器件(OLED),其结构为ITO/MoO₃(60nm)/NPB(40nm)/TCTA(x nm,x＝0、5、10和15)/CPB:GIr1:R -4B(30nm,14%,2%) /BCP(10nm) /Alq₃(40nm)/LiF(1nm)/Al( 100nm)。其中x＝0,5,10,5nm。通过在发光层与空穴传输层之间增 加电子阻挡层TCTA,使器件的效率得到提高。当TCTA厚为10nm时, 起亮电压为4V左右,器 件的最大发光效率为20.2cd/A,最高亮度可以达到21840cd/m²,器件的色坐标 为(0.42,0.53)。器件的EL主峰位于524nm 和604nm。并且当电流 密度为2.49mA/cm²时,10nm厚的TCTA 电子阻挡层的器件发光效率是不加入TCTA的器件发光效率的2倍。发光效率的提高是由于电 子阻挡层的加入限制了空穴传输层NPB的发光,从而使更多的激子在发光层中复合。     

通过引入电子阻挡层的高效率的有机磷光白光器件

以CBP作为母体材料,绿色磷光染料Ir(ppy)3作为敏化剂,以荧光染料rubrene作为受主,制备了结构为ITO/2T-NATA(25 nm)/ NPBX (25-d nm)/ CBP:5%Ir(ppy)3:0.5%Rubrene(8 nm)/NPBX(d nm)/DPVBi(30 nm)/TPBi(20 nm)/Alq(10 nm)/LiF(1 nm)/Al的白光器件.在器件中,敏化剂Ir(ppy)3、荧光染料rubrene的浓度分别为5.0 wt%和0.5 wt%,发光层的厚度选择8 nm,通过调整两层NPBX的厚度来改善器件的性能,得到了比较理想的白光发射.当d的厚度为10 nm 时,器件在7 V的电压下最大电流效率达到11.2 cd/A,在17 V的电压下其最大亮度达到28 170 cd/m2,色坐标为(0.37,0.42),处于白光区.     

磷光与荧光相结合的多层白色有机发光器件

采用真空热蒸镀的方法制备了磷光与荧光相结合的 多层白色有机电致发光器件(OLED)。将绿 光磷光掺杂染料掺杂到母体CBP中作为绿光发光层;荧光材料 DCM2以亚单层的方式插入Alq₃中作为红光发光层;DPVBi为蓝光发光层。器件的结构为ITO /NPB(40nm)/DPVBi(d nm)/CBP:Ir(ppy)₃₈%(5nm)/ Alq₃(5nm)/DCM2(0.05nm)/Alq₃(45nm)/LiF(1nm)/AI(200nm)。实验中通过改变蓝光发 光层的厚度,得到了高效率的 白光OLED,器件的最大电流效率可达6.75cd/A,最大功率效率达2.67lm/W,最大亮度 达30440cd/m²。此外,当电压从4V变化到14V时色坐标从(0.59,0.39)变化到(0.35,0.38), 基本处于白光区。本文器件的特点在于其性能可以通过简单调整DPVBi的厚度,避免 了使用多掺杂层工艺的复杂性。     

以9,99'-联蒽和红荧烯为发光层的白色OLED研制

利用旋涂技术,将蓝光材料9,9'-bianthracene和黄光材料rubrene以一定的比例混合达到白光的效果,制备了白色有机电致发光器件(WOLED).当掺杂比为0.9%时得到近白光器件,色坐标为(0.308,0.347),器件的启亮电压为8 V,当外加电压达到25 V时,器件发光亮度达3120 cd/m2.     

一种新的多发光层白色有机电致发光器件

采用多发光层结构,将一种新型的黄橙色荧光染料2-溴-4-氟苯乙烯-8-羟基喹啉锌(BFHQZn,(E)-2-(2-bronw-4-fluorostyryl)quinolato-Zinc)与蓝色9,10-二-2-蔡蔥(ADN)组合在一起实现白光.研究了插入4,4-N,N-二咔唑联苯(CBP)对器件色度的影响,通过改变发光...     

基于CzHQZn发光的白光有机电致发光器件

利用一种新材料(E)-2-(2-(9-ethyl-9H-carbazol-3-yl)vinyl)quinolato-Zinc(CzHQZn)作空穴传输层和发光层制备了白光有机电致发光器件(WOLED),器件的结构为indium-tin oxide(ITO)/4,4′,4′′-{N,-(2-naphthyl)-N-phenylamino}-triphenylamine(2T-NATA)(22 nm)/CzHQZn(xnm)/N,N′-bis-(1-naphthyl)-N,N′-diphenyl-1,1′-biphenyl-4,4′-diamine(NPBX)(ynm)/2,9-dimethyl,-4,7-diaphenyl,1,10-phenanthroline(BCP)(10nm)/tris(8-quinolinolato)aluminum(Alq3)(68-x-ynm)/LiF(0.5 nm)/Al。研究发现发光层CzHQZn和NPBX的厚度对器件的发光性能有较大的影响。当CzHQZn厚度x为22 nm、NPBX厚度y为8 mm时,得到了色度最好和效率最大的WOLED,最大电流效率为0.9 cd/A(at ...     

2-TNATA对蓝与黄二基色分离的堆叠式白色有机发光器件性能的影响(英文)

研究了2-TNATA厚度对蓝与黄二基色分离的堆叠式白色有机发光器件性能的影响。器件结构为:2-TNATA(xnm)/NPB(25nm)/ADN(30nm)∶TBPE(2%)∶DCJTB(1%)/Alq3(20nm)/LiF(1nm)/Al(100nm)。根据实验结果,2-TNATA的厚度对载流子的注入、色稳定性、热稳定性影响明显。发光器件的颜色可以通过改变加入的2-TNATA层的厚度来改变。这种器件使用2-TNATA作为空穴注入层显示出了色纯度高的白光发射,CIE色坐标x=0.3197,y=0.3496,亮度能够达到12230cd/m2。     

新型低压高效叠层有机白光器件

以Bphen:Li/WO3作为电荷产生层制备了低压、高效有机叠层白光器件. 实验中,首先在器件中引入高导电性的载流子注入和传输层,有效降低了器件的驱动电压,然后通过电荷产生层垂直堆叠两个低压白光器件,获得了低压、高效有机叠层白光器件. 叠层器件性能与单发光单元的器件相比较,其亮度及效率均有大幅提高,叠层器件的最大电流效率达到了17cd/A,在相同的电流密度下,叠层器件的效率约为传统器件的2.3倍,同时由于在叠层结构中引入了高导电性的载流子传输层,有效降低了器件的驱动电压,显著改善了白光器件的流明效率.叠层器件的流明效率相对于单发光单元器件提高了53%.     

新型低压高效叠层有机白光器件

以Bphen:Li/WO3作为电荷产生层制备了低压、高效有机叠层白光器件.实验中,首先在器件中引入高导电性的载流子注入和传输层,有效降低了器件的驱动电压,然后通过电荷产生层垂直堆叠两个低压白光器件,获得了低压、高效有机叠层白光器件.叠层器件性能与单发光单元的器件相比较.其亮度及效率均有大幅提高,叠层器件的最大电流效率达到了17cd/A,在相同的电流密度下,叠层器件的效率约为传统器件的2.3倍.同时由于在叠层结构中引入了高导电性的载流子传输层,有效降低了器件的驱动电压,显著改善了白光器件的流明效率.叠层器件的流明效率相对于单发光单元器件提高了53%.     

Highly Efficient Warm White Organic Light‐Emitting Diodes by Triplet Exciton Conversion

White organic light‐emitting diodes (WOLEDs) are currently under intensive research and development worldwide as a new generation light source to replace problematic incandescent bulbs and fluorescent tubes. One of the major challenges facing WOLEDs has been to achieve high energy efficiency and high color rendering index simultaneously to make the technology competitive against other alternative technologies such as inorganic LEDs. Here, an all‐phosphor, four‐color WOLEDs is presented, employing a novel device design principle utilizing molecular energy transfer or, specifically, triplet exciton conversion within common organic layers in a cascaded emissive zone configuration to achieve exceptional performance: an 24.5% external quantum efficiency (EQE) at 1000 cd/m² with a color rendering index (CRI) of 81, and an EQE at 5000 cd/m² of 20.4% with a CRI of 85, using standard phosphors. The EQEs achieved are the highest reported to date among WOLEDs of single or multiple emitters possessing such high CRI, which represents a significant step towards the realization of WOLEDs in solid‐state lighting.     

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.     

白光有机电致发光器件的研究

白光有机电致发光器件在显示和照明领域有着极大的应用前景，受到人们广泛的关注。本文对白光有机电致发光器件的结构、工作原理、工艺流程、存在的问题等进行了简单的概述，力求总结出制备白光有机发光器件的新途径。     

Efficiency Enhancement of Organic Light‐Emitting Diodes Incorporating a Highly Oriented Thermally Activated Delayed Fluorescence Emitter

An organic light‐emitting diode (OLED) with the blue emitter CC2TA showing thermally activated delayed fluorescence (TADF) is presented exhibiting an external quantum efficiency () of 11% ± 1%, which clearly exceeds the classical limit for fluorescent OLEDs. The analysis of the emission layer by angular dependent photoluminescence (PL) measurements shows a very high degree of 92% horizontally oriented transition dipole moments. Excited states lifetime measurements of the prompt fluorescent component under PL excitation yield a radiative quantum efficiency of 55% of the emitting species. Thus, the radiative exciton fraction has to be significantly higher than 25% due to TADF. Performing a simulation based efficiency analysis for the OLED under investigation allows for a quantification of individual contributions to the efficiency increase originating from horizontal emitter orientation and TADF. Remarkably, the strong horizontal emitter orientation leads to a light‐outcoupling efficiency of more than 30%.     

Exciton‐Adjustable Interlayers for High Efficiency,Low Efficiency Roll‐Off,and Lifetime Improved Warm White Organic Light‐Emitting Diodes (WOLEDs) Based on a Delayed Fluorescence Assistant Host

Recently, a new route to achieve 100% internal quantum efficiency white organic light‐emitting diodes (WOLEDs) is proposed by utilizing noble‐metal‐free thermally activated delayed fluorescence (TADF) emitters due to the radiative contributions of triplet excitons by effective reverse intersystem crossing. However, a systematic understanding of their reliability and internal degradation mechanisms is still deficient. Here, it demonstrates high performance and operational stable purely organic fluorescent WOLEDs consisting of a TADF assistant host via a strategic exciton management by multi‐interlayers. By introducing such interlayers, carrier recombination zone could be controlled to suppress the generally unavoidable quenching of long‐range triplet excitons, successfully achieving remarkable external quantum efficiency of 15.1%, maximum power efficiency of 48.9 lm W⁻¹, and extended LT50 lifetime (time to 50% of initial luminance of 1000 cd m⁻²) exceeding 2000 h. To this knowledge, this is the first pioneering work for realizing high efficiency, low efficiency roll‐off, and operational stable WOLEDs based on a TADF assistant host. The current findings also indicate that broadening the carrier recombination region in both interlayers and yellow emitting layer as well as restraining exciplex quenching at carrier blocking interface make significant roles on reduced efficiency roll‐off and enhanced operational lifetime.     

Manipulation of Charge and Exciton Distribution Based on Blue Aggregation‐Induced Emission Fluorophors: A Novel Concept to Achieve High‐Performance Hybrid White Organic Light‐Emitting Diodes

The aggregation‐induced emission (AIE) phenomenon is important in organic light‐emitting diodes (OLEDs), for it can potentially solve the aggregation‐caused quenching problem. However, the performance of AIE fluorophor‐based OLEDs (AIE OLEDs) is unsatisfactory, particularly for deep‐blue devices (CIEy < 0.15). Here, by enhancing the device engineering, a deep‐blue AIE OLED exhibits low voltage (i.e., 2.75 V at 1 cd m^?2), high luminance (17 721 cd m^?2), high efficiency (4.3 lm W^?1), and low efficiency roll‐off (3.6 lm W^?1 at 1000 cd m^?2), which is the best deep‐blue AIE OLED. Then, blue AIE fluorophors, for the first time, have been demonstrated to achieve high‐performance hybrid white OLEDs (WOLEDs). The two‐color WOLEDs exhibit i) stable colors and the highest efficiency among pure‐white hybrid WOLEDs (32.0 lm W^?1); ii) stable colors, high efficiency, and very low efficiency roll‐off; or iii) unprecedented efficiencies at high luminances (i.e., 70.2 cd A^?1, 43.4 lm W^?1 at 10 000 cd m^?2). Moreover, a three‐color WOLED exhibits wide correlated color temperatures (10 690–2328 K), which is the first hybrid WOLED showing sunlight‐style emission. These findings will open a novel concept that blue AIE fluorophors are promising candidates to develop high‐performance hybrid WOLEDs, which have a bright prospect for the future displays and lightings.     

Investigating the Role of Emissive Layer Architecture on the Exciton Recombination Zone in Organic Light‐Emitting Devices

An experimental approach to determine the spatial extent and location of the exciton recombination zone in an organic light‐emitting device (OLED) is demonstrated. This technique is applicable to a wide variety of OLED structures and is used to examine OLEDs which have a double‐ (D‐EML), mixed‐ (M‐EML), or graded‐emissive layer (G‐EML) architecture. The location of exciton recombination in an OLED is an important design parameter, as the local optical field sensed by the exciton greatly determines the efficiency and angular distribution of far‐field light extraction. The spatial extent of exciton recombination is an important parameter that can strongly impact exciton quenching and OLED efficiency, particularly under high excitation. A direct measurement of the exciton density profile is achieved through the inclusion of a thin, exciton sensitizing strip in the OLED emissive layer which locally quenches guest excitons and whose position in the emissive layer can be translated across the device to probe exciton formation. In the case of the G‐EML device architecture, an electronic model is developed to predict the location and extent of the exciton density profile by considering the drift, diffusion, and recombination of charge carriers within the device.