1. 聊城大学 物理科学与信息工程学院, 山东 聊城 252059
2. 山东省光通信科学与技术重点实验室,山东 聊城,252059
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刘婷婷, 李淑红, 王文军等. 基于器件结构提高TADF-OLED器件的发光性能[J]. 发光学报, 2020,41(1): 77-85
LIU Ting-ting, LI Shu-hong, WANG Wen-jun etc. Enhanced Luminescent Properties of TADF-OLEDs Based on Device Structures[J]. Chinese Journal of Luminescence, 2020,41(1): 77-85
刘婷婷, 李淑红, 王文军等. 基于器件结构提高TADF-OLED器件的发光性能[J]. 发光学报, 2020,41(1): 77-85 DOI： 10.3788/fgxb20204101.0077.
LIU Ting-ting, LI Shu-hong, WANG Wen-jun etc. Enhanced Luminescent Properties of TADF-OLEDs Based on Device Structures[J]. Chinese Journal of Luminescence, 2020,41(1): 77-85 DOI： 10.3788/fgxb20204101.0077.
为了提高以TADF材料作为主体、天蓝色荧光材料作为客体的混合薄膜的OLED器件光电性能，我们调整了器件结构，使主体材料发挥其优势。制备了基本结构为ITO/NPB（40 nm）/DMAC-DPS:,x,% BUBD-1（40 nm）/Bphen（30 nm）/LiF（0.5 nm）/Al的OLED器件。研究了主-客体材料在不同掺杂浓度下的OLED器件的光电特性。为了提高主体材料的利用率，在空穴传输层和发光层之间加入10 nm的DMAC-DPS作为间隔层；然后，在阳极和空穴传输层之间加入HAT-CN作为空穴注入层，形成HAT-CN/NPB结构的PN结，有效降低了器件的启亮电压（2.7 V）。测量了有无HAT-CN的单空穴器件的阻抗谱。结果表明，在最佳掺杂比例（2%）下，器件的外量子效率（EQE）达到4.92%，接近荧光OLED的EQE理论极限值；加入10 nm的DMAC-DPS作为间隔层，使得器件的EQE达到5.37%；HAT-CN/NPB结构的PN结有效地降低了器件的启亮电压（2.7 V），将OLED器件的EQE提高到5.76%；HAT-CN的加入提高了器件的空穴迁移率，降低了单空穴器件的阻抗。TADF材料作为主体材料在提高OLED器件的光电性能方面具有很大的潜力。
In order to improve the optoelectronic properties of organic light emitting diodes (OLEDs) with a hybrid film as the light emitting layer, which included the thermally activated delayed fluorescent (TADF) as host matrix and the sky-blue fluorescent material guest, we adjusted the device structures properly to improve the utilization rate of the host material. The basic structure of OLED is ITO/NPB(40 nm)/DMAC-DPS:,x,% BUBD-1(40 nm)/Bphen(30 nm)/LiF(0.5 nm)/Al. First, the optoelectronic properties of host-guest OLED devices was studied with different doping ratio. Then, the DMAC-DPS (10 nm) was evaporated between the hole transport layer and the emission layer, it improved the utilization rate of the host material. Moreover, an organic material HAT-CN was added as the hole injection layer between the anode and the hole transport layer with the method of vacuum evaporation. Finally, the hole-only devices with or without HAT-CN were fabricated for the impedance spectra. The results indicated that the external quantum efficiency (EQE) of 4.92% was acquired at the optimal doping ratio (2%), it approached the theoretical EQE limit of the fluorescent OLEDs. The DMAC-DPS (10 nm) between the hole transport layer and the emission layer improved the utilization rate of the host material, led to a higher EQE of 5.37%, and breaked the limit of 5% of the EQE of traditional fluorescent OLEDs. The HAT-CN/NPB heterojunction units effectively reduced the driving voltage of OLEDs (2.7 V), and the maximum EQE increased to 5.76% at the same time. Additionally, From the lg,J,-lg,V, curves and the impedance spectrum analysis, the hole-only devices with HAT-CN improved the hole mobility and reduced the impedance of the devices. This study shows that TADF materials have great potential in enhancing the optoelectronic performance of OLEDs.
thermally activated delayed fluorescent (TADF)TADF-OLEDdevice structure hole only devicesimpedance spectrum
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