【作者】 张君；

【导师】 朱旭辉；

【作者基本信息】 华南理工大学 ， 材料科学与工程， 2024， 博士

【摘要】 有机发光二极管（OLED）显示技术因其自发光、迅速响应、广视角、对比度高等优异特性,正在引领显示技术的革新潮流。鉴于OLED商业化进程的迅速推进,特别是在显示领域,如何提升全彩显示的效率与稳定性,已成为学术界与产业界共同面对的关键挑战。这一挑战亟待双方持续聚焦并深入探索,以推动OLED技术的进一步发展与应用。为了满足应用需求,蒸镀型OLED功能材料,诸如有机电子传输材料、有机发光层主体材料以及有机空穴注入/传输材料等,不仅要求兼具高载流子迁移率和玻璃化转变温度（T_g≥120℃）,而且还需考虑合成简捷、热稳定性及纯度等因素。另外一方面,低热稳定性杂质的存在不利于OLED功能材料在持续工作条件下的长期稳定性。芳香膦氧基团,其刚性与立体结构的结合,成为构筑非晶态OLED功能材料的理想选择。同时,该基团的强吸电性可有效降低所制备材料的前线轨道能级。此外,值得指出的是,芳香膦氧单元的四面体型结构有助于改善目标产物的溶解性,调控分子间相互作用,进而简化纯化过程,如消除卤素杂质等对OLED器件稳定性的潜在影响。基于此,本论文合成制备了一系列兼具高纯度和高玻璃化温度的芳香膦氧基团修饰的化合物,并且用于OLED器件的蓝光发光层主体、电子传输/空穴阻挡层,以及叠层OLED器件的电子产生层。具体研究内容如下:（1）提出了一类经Suzuki偶联,从卤代芳基膦氧或芳基膦氧硼酸酯制备高纯度芳香膦氧化合物的简捷方法。该方法以卤代芳基膦氧或芳基膦氧硼酸酯为原料,通过Suzuki反应高效制备目标化合物。然而,产物中常残留芳基硼酸/硼酸衍生物,其极性与目标产物相近,造成分离困难。特别是,芳基硼酸经脱水易形成潜在的低聚体。为此,我们提出以过氧化物氧化剂与碱的协同作用,使其中残留的芳基硼酸/硼酸衍生物定量地转化为相应的弱极性的酚衍生物（伴随酚钠的产生）或进一步的氧化产物---醌衍生物;然后利用所得的酚（醌）衍生物、酚钠和芳香膦氧产物之间分子极性的差异,通过柱层析分离提纯,实现了高效纯化。通过该方法,制备了一系列芳基膦氧基团修饰的功能化合物,如mTPO-An-BB、mTPO-An-BP、Phen-SBFDPO和mTPO-An-TRZ等,其HPLC纯度均可达到99.90%以上。（2）分别以（3-溴苯基）二苯基膦氧、二苯基（3-（4,4,5,5-四甲基-1,3,2-二氧硼杂环戊烷-2-基）苯基）膦氧为原料,经Suzuki偶联,合成了蒽衍生物10-（4-苯基苯基）-9-（3-二苯膦酰基苯基）蒽（mTPO-An-BB）和10-（4-（菲-9-基）苯基）-9-（3-二苯膦酰基苯基）蒽（mTPO-An-BP）。mTPO-An-BB:HOMO=-5.98 eV,LUMO≈-3.09 eV,HPLC纯度约99.99%,固态光致发光峰位于438 nm;mTPO-An-BP:HOMO=-5.6 eV,LUMO≈-2.72eV,HPLC纯度约99.94%,固态光致发光峰位于437 nm。以mTPO-An-BB和mTPO-An-BP作为蓝光主体,所制备的深蓝光OLED器件（ITO/HTL:p-dopant（10 nm,3%）/HTL（50 nm）/EBL（10 nm）/mTPO-An-BB（mTPO-An-BP）:BD（3%,20 nm）/ETL:Liq（35 nm,50%）/Yb（1 nm）/Ag（100 nm））的最大电流效率分别为4.10、3.77 cd A^-1;对应的EQE分别为4.24%、3.60%;电致发光峰位于462、464 nm,半峰宽为26、28 nm;CIE（0.128,0.118）、CIE（0.127,0.132）;在ca.1000 cd m^-2亮度下,CE分别为4.1和3.6 cd A^-1。遗憾的是,两者的器件稳定性t₉₅@1000 cd m^-2只有几个小时。为了进一步了解mTPO-An-BB（HOMO=-5.98 eV）在OLED器件中的稳定性,以其为电子传输/空穴阻挡层,制备了蓝光OLED器件。其最大电流效率为5.24 cd A^-1@ca.3595 cd m^-2;对应的EQE为5.49%,并且具有低效率滚降;电致发光峰位于463 nm,半峰宽为26 nm,CIE（0.126,0.117）;在ca.9100 cd m^-2亮度下,CE为5.08 cd A^-1。值得指出的是,外推的器件稳定性LT95@1000 cd m^-2达到540小时。（3）利用3-（7-二苯基膦酰基-9,9’-螺双[芴]-2-基）-1,10-菲啰啉（Phen-SBFDPO）作为电子产生层,应用于高效率、高稳定的叠层窄谱带蓝光OLED器件。前期,通过2,7-螺二芴单元,以二苯基膦酰基团与1,10-菲啰啉-3-基相连,研发了菲啰啉衍生物Phen-SBFDPO（T_g=172 ℃）。HOMO=-6.06 eV,LUMO≈-2.86 eV;Phen-SBFDPO的电子迁移率约为3.68×10^-5cm² V^-1 s^-1。以Phen-SBFDPO:2 wt%Yb作为电子产生层,构筑“叠层”蓝光OLED器件。CE=9.1 cd A^-1,EQE=10.3%@1000 cd m^-2;电致发光峰位于461 nm,半峰宽为23 nm,色坐标CIE（0.13,0.10）。叠层蓝光器件稳定性LT95达到994.9 h@1000 cd m^-2。更多还原

【Abstract】 Organic light-emitting diodes（OLEDs）is leading the display technology innovation due to its outstanding characteristics such as self-illumination,fast response,wide viewing angle,and high contrast.In view of the rapid advancement of OLED commercialization,especially in the display fields,how to improve the efficiency and stability of full-color display has become a key challenge faced by both academia and industry.This challenge requires to continue to explore in depth to promote the further development of OLED technology.In order to meet practical applications,OLED materials deposited by thermal evaporation,such as organic electron-transport materials,hosts of the organic light-emitting layers,and organic hole-injection/transport materials,not only possess high carrier mobility and glass transition temperature（T_g≥120°C）,but also are required to take into considerations the factors such as ease of synthesis,high thermal stability and purity.On the other hand,the existence of low thermally stable impurities may facilitate decomposition of OLED materials in extended and continuous working conditions.The strong electron-withdrawing property of the P=O group can effectively reduce the front orbital energy levels.In addition,it is worth pointing out that the tetrahedral structure of the arylphosphine oxide units can help to improve the solubility of the target products,control the intermolecular interactions,and thus simplify the purification process,such as eliminating the potential effects of halogen impurities on the stability of OLED devices.In this paper,a series of arylphosphine oxide moiety-modified organic functional compounds with high purity and high glass transition temperature were synthesized,which are characterized as the host of blue light-emitting layer,or electron-transport/hole-blocking layer in deep blue OLEDs or the electron-generation layer of stacked OLEDs.The detailed contents are as follows:（1）We propose a facile method for the preparation of high-purity arylphosphine oxide moieties-functionalized organic compounds via Suzuki coupling.In this method,halogenated arylphosphonic oxides or arylphosphine oxide boron esters are used as starting materials.However,aryl boronic acid/boric acid derivatives often remain in the product,and their polarity is similar to that of the target product,resulting in difficult separation.In particular,aryl boronic acids are prone to the formation of potential oligomers after dehydration.Therefore,we utilize the synergistic effect of peroxide oxidant and alkali to quantitatively convert the residual aryl boronic acids/boric acid derivatives into the corresponding weakly polar aryl alcohols（accompanied by the formation of sodium aryl alcoholates）or further oxidation products-quinone derivatives,which are thus separated and purified by column chromatography.Consequently,a series of functional compounds modified by arylphosphine oxide moieties,such as mTPO-An-BB,mTPO-An-BP,Phen-SBFDPO and mTPO-An-TRZ,is obtained with their HPLC purity of over 99.90%.（2）Anthracene derivatives 10-（4-phenylphenyl）-9-（3-diphenylphosphinylphenyl）-anthracene（mTPO-An-BB）and 10-（4-（phenanthren-9-yl）phenyl）-9-（3-diphenylphosphinyl-phenyl）anthracene（mTPO-An-BP）were synthesized by starting from（3-bromophenyl）diphenylphosphine oxide and diphenyl（3-（4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl）phenyl）phosphine oxide,respectively.mTPO-An-BB:HOMO=-5.98 eV,LUMO≈-3.08eV,HPLC purity:99.99%,solid-state photoluminescence peak at 438 nm;mTPO-An-BP:HOMO=-5.6 eV,LUMO≈-2.71 eV,HPLC purity:99.94%,solid-state photoluminescence peak at 437 nm.mTPO-An-BB and mTPO-An-BP are used respectively as the host of the deep blue emitter in OLEDs（ITO/HTL:p-dopant（10 nm,3%）/HTL（50 nm）/EBL（10 nm）/mTPO-An-BB or mTPO-An-BP:BD（3%,20 nm）/ETL:Liq（35 nm,50%）/Yb（1 nm）/Ag（100 nm））.The deep blue OLEDs show a maximum current efficiency of 4.10 and 3.77 cd A^-1,corresponding to EQE of 4.24%and 3.60%,respectively.The electroluminescence peaks are located at 462-464 nm with FWHM（full width at half maximum）=26-28 nm.CIE color coordinates are（0.128,0.118）and（0.127,0.132）,respectively.At a luminance of 1000 cd m^-2,CE remains 4.1 and 3.6 cd A^-1,respectively.Unfortunately,both devices have operational stability of LT95@1000 cd m^-2 for only a few hours.Further,mTPO-An-BB（HOMO=-5.98 eV）is investigated as an electron-transport/hole-blocking layer in the analogue deep blue OLED.It has a maximum current efficiency of5.24 cd A^-1@ca.3595 cd m^-2 with a corresponding EQE of 5.49%and low-efficiency roll-off.The electroluminescence peak is located at 463 nm,FWHM=26 nm,CIE（0.126,0.117）.At a luminance of 9100 cd m^-2,CE is 5.08 cd A^-1.It is worth pointing out that the extrapolated device stability LT95@1000 cd m^-2 reaches 540 h.（3）3-（7-diphenylphosphinyl-9,9’-spirobis[fluoren]-2-yl）-1,10-phenanthroline（Phen-SBFDPO,T_g=172 ℃）is used as an electron-generating layer for efficient and stable tandem narrowband blue OLED.Previously,Phen-SBFDPO was developed by our group using a2,7-spirofluorene unit to link 1,10-phenanthroline-3-yl moiety with a diphenylphosphinyl group.HOMO=-6.06 eV,LUMO≈-2.86 eV.The electron mobility of Phen-SBFDPO is about 3.68×10^-5 cm² V^-1 s^-1.Consequently,Phen-SBFDPO:2wt%Yb was used as the electron generation layer to construct a"tandem"（two-stacked）blue OLED.CE=9.1 cd A^-1,EQE=10.3%@1000 cd m^-2,electroluminescence peak at 461 nm,FWHM=23 nm,CIE（0.13,0.10）.The tandem OLED showed high stability with LT95=994.9 h@1000 cd m^-2.更多还原