【作者】 刘源；

【导师】 杨楚罗；

【作者基本信息】 武汉大学 ， 有机化学， 2016， 博士

【摘要】 有机光电功能材料是光电器件的研究基础。本论文设计合成了一系列星型化合物光电功能材料,结合其各自的结构特点,分别研究了它们作为聚合物太阳能电池的界面材料、钙钛矿太阳能电池的空穴传输材料和热活化延迟荧光材料的应用。第一章：简要介绍了聚合物太阳能电池的电极界面修饰材料、钙钛矿太阳能电池的空穴传输材料和热活化延迟荧光材料的研究背景和现状,并针对各个领域存在的问题提出论文的研究思路。第二章：将二乙胺基和磷酸二乙酯基极性基团引入到六芴基苯结构中,设计合成了四个醇溶性界面材料Tn0、Tn1、Tp0和Tpl,其中Tnl和Tpl具有更大的分子骨架和疏水性烷基链。ITO电极通过Tn0、 Tp0、Tn1和Tpl修饰时的功函数均显著降低。采用Tn0和Tnl做为ITO电极界面修饰材料的倒置聚合物太阳能电池实现了良好的器件性能,其能量转换效率(PCE)分别达到8.62%和8.80%。与Tn0、Tn1相比,TpO、Tp1的界面粗糙度较大,器件PCE分别为5.30%和5.12%。与Tn0相比,Tnl的界面更加疏水,有利于活性层的铺展,使得活性层薄膜形貌更好,器件效果也相对较好。第三章：设计合成了四个基于均三嗪为核的星型共轭结构的界面材料Tfl、Tf2、Tf1OH和Tf2OH,其中Tf2和Tf20H具有更大的分子骨架和疏水性烷基链。二乙胺基或氮羟乙基等极性基团赋予了材料良好的醇溶性和界面修饰性能。这些材料修饰后的ITO电极功函数显著降低,与PC71BM形成欧姆接触,降低了电子的提取势垒。ITO电极功函数的降低程度与界面材料的厚度有关。将Tfl,Tf2, Tf1OH和Tf20H作为阴极修饰材料应用于倒置聚合物太阳能电池分别获得了8.97%,8.33%,8.89%和8.15%的能量转换效率。由于Tfl的界面偶极最强,在Tfl界面处的电子分离和提取过程相比其他材料更加高效。第四章：设计合成了四个二乙胺基修饰的以三苯基胺或三苯基硼为中心核、芴为臂的星型化合物TA1、TA2、TB1和TB2。这些材料均可以明显降低ITO电极的功函数,且采用吸电子中心核的TB1和TB2相较于采用给电子中心核的TA1和TA2,其降低作用更强,表明吸电子基团与极性基团协同作用,形成强度更大的界面偶极。电子在界面处的分离和提取受界面偶极的影响,随着界面偶极的增大,其分离和提取过程更加高效。第五章：将甲氧基二苯胺空穴传输单元通过芴桥或苯桥连接到苯环或均三嗪中心核上,设计合成了五个具有星型结构的化合物TFB-OMeDPA、TFT-OMeDPA、 TPT-OMeDPA、HFB-OMeDPA和HPB-OMeDPA。根据中心核和π桥的不同,化合物呈现出光物理、电化学和热力学性质等的差异。芴桥上的柔性烷基链显著增强了材料的溶解性。五个化合物均具有匹配的最高占据轨道能级。HFB-OMeDPA和HPB-OMeDPA具有较好的空穴传输能力,其空穴迁移率分别为1.45×10-5cm2v-1S-1和1.15×10-5 cm2v-1s-1。将HPB-OMeDPA和]HFB-OMeDPA作为空穴传输材料制备的钙钛矿太阳能电池器件取得了良好的器件效果,其能量转换效率分别达到13.9%和12.2%。同时,基于HFB-OMeDPA的器件迟滞效应较不明显。第六章：设计合成了一类具有四面体构型的化合物C-OMeTPA、Si-OMeTPA、 Ge-OMeTPA、AD-OMeTPA和ADP-OMeTPA,其中心核分别为碳、硅、锗原子和金刚烷,外围连接对甲氧基三苯胺单元,并进一步引入苯环扩大局部共轭。与Ge-OMeTPA相比,局部共轭增强的ADP-OMeTPA的空穴迁移能力明显提高,Ge-OMeTPA和ADP-OMeTPA的空穴迁移率分别为1.4×10-6 cm2 V-1s-1和3.0 x 10-5 cm2 V-1s-1。由于空穴传输能力的差异,基于ADP-OMeTPA为空穴传输材料的钙钛矿太阳能电池器件的实现了13.8%的能量转换效率,显著高于基于Ge-OMeTPA的器件性能。第七章：将咔唑单元通过2位或3位与中心苯环相连,设计合成了螺旋桨构型的六咔唑基苯化合物H2CzB和H3CzB。连接位点的不同显著影响化合物的光物理和电化学性质。H2CzB和H3CzB的HOMO能级分别为-5.40和-5.18 eV。由于高度扭曲的刚性结构,H2CzB和H3CzB均具较大的光学带隙,分别为3.28和3.36 eV。通过空间电荷限制电流测得H2CzB和H3CzB的空穴迁移率分别为1.98×10-5 cm2v-s-1和1.89×10-6 cm2v-1s-1,其中H2CzB与Spiro-OMeTAD的空穴传输能力接近,表明H2CzB做为空穴传输材料的应用潜力。第八章：将三苯基硼作为受体单元引入到热活化延迟荧光材料的设计中,合成了三个基于三苯基硼/吩恶嗪杂化的热活化延迟荧光材料TB-1PXZ, TB-2PXZ和TB-3PXZ。随着化合物中给体单元数目的增多,化合物的最低单线态-三线态能极差逐渐从0.12 eV减小到0.01 eV,反向隙间穿越常数逐渐从0.60×107 s-1增大到19.47×107 s-1,反向隙间穿越过程更加高效。同时随着外围吩恶嗪单元数目增多,分子结构更加刚性,其荧光量子产率从0.12升高到0.95。基于TB-3PXZ的溶液加工器件实现了41.5 cdA-1的最大电流效率,32.6 lm W-1的最大功率效率和13.9%的最大外量子效率,是基于溶液旋涂型含硼发光材料的最高效率之一。同时,由于高效的隙间穿越过程降低了三线态激子浓度,器件效率滚降十分缓慢。更多还原

【Abstract】 Organic optoelectronic functional materials are the foundation of optoelectronic devices. In this paper, a series of star-shaped materials with different optoelectronic functions are designed and synthesized. Devices based on these functional materials as the interlayer for polymer solar cells, the hole transport material for perovskite solar cells and thermally activated delayed fluorescence emitter for organic light-emitting diodes are fabricated, and their structure-property relationships are discussed.In chapter 1, we give a brief introduction of the background of the interlayer for polymer solar cells, the hole transport material for perovskite solar cells and thermally activated delayed fluorescence material, and then propose the research ideas of this thesis.Chapter 2:four alcohol-soluble interlayers, namely TnO, Tnl, TpO and Tp1 were designed and synthesized by introducing diethylamino or phosphate polar groups into the molecules, in which Tnl and Tpl possess additional extended skeleton and hydrophobic alkyl chains. The work function of ITO significantly decreasd after modified by TnO, Tnl, TpO and Tp1. Utilzing TnO and Tnl as interlayres, the inverted polymer solar cells achieved good device performance, with the power conversion efficiencies of 8.62% and 8.80%, respectively. Compared with TnO and Tnl, TpO and Tpl exhibit relatively rough surface, resulting in PCE of 5.30% and 5.12%. Compared with TnO, Tnl is more hydrophobic, which facilitates the active layer spreading out and obtain a better morphology, thus enhanced the device performance.Chapter 3:four star-shaped conjugated compounds with 1,3,5-triazine as a core and fluorene as the arms, namely Tfl, Tf2, Tf1OH and Tf2OH, were designed and synthesized. Compared with Tfl and Tf1OH, Tf2 and Tf2OH possess more π-extended structure and additional n-hexyl chains in the inner fluorene arms. Owing to the diethylamino or diethanolamino end groups, all the compounds exhibited excellent alcohol solubility and interface modification ability. by reducing the work function of ITO effectively. Enhanced device performances were obtained by incorporating these compounds as the cathode interlayers in inverted polymer solar cells with the power conversion efficiency reached 8.97%,8.33%,8.89% and 8.15%, respectively. Since Tfl exhibit the strongest interface dipole among them, the electron separation and extraction process at the interface Tfl are more efficient.Chapter 4:four star-shaped diethylamino functional materials modified with triphenylamine or triphenyl boron as cores and fluorene as the arms were designed and synthesized, namely TA1, TA2, TB1 and TB2. All these materials exhibited remarkable ability to decrease the work function of ITO electrode. Compared with the electron-donating units cored materials of TA1 and TA2, TB1 and TB2 with a electron-withdrawing central core can lower the work function more effectively, which indicate that the electron withdrawing group and polar group group have an synergistic effect and then generating a larger interfacial dipole.Chapter 5:five star-shaped compounds, namely, TFB-OMeDPA, TFT-OMeDPA, TPT-OMeDPA, HFB-OMeDPA and HPB-OMeDPA were designed and synthesized, with the methoxy diphenylamine hole transport units at periphery, fluorene or benzene as π-bridges and benzene ring or triazine as the central core. Varied with the central core and π bridge, the compounds exhibited significant differences in photophysical, electrochemical and thermodynamic properties. Flexible alkyl chain in the fluorene bridge significantly enhance the solubility of the material. Five compounds exhibited suitable HOMO levels. HFB-OMeDPA and HPB-OMeDPA showed good hole transporting ability, with the hole mobility of 1.45 x 10-5 cm2 V-1 s-1 and 1.15 x 10-5 cm2 V-1 s-1, respectively. Perovskite solar cells based on HPB-OMeDPA and HFB-OMeDPA as the hole transport materials achieved good performances, with the power conversion efficiencies of 13.9% and 12.2%, respectively. Moreover, HFB-OMeDPA-based device exhibited less hysteresis.Chapter 6:a series of tetrahedral configurational compounds, namely C-OMeTPA, Si-OMeTPA, Ge-OMeTPA, AD-OMeTPA and ADP-OMeTPA were designed and synthesized. The central cores vary from carbon, silicon, germanium atoms to adamantane, with methoxy-triphenylamine units as the periphery. The, the hole mobility of Ge-OMeTPA and ADP-OMeTPA are 1.4×10-6 cm2 V-1 s-1 and 3.0×10-5 cm2 V-1 s-1, respectively. ADP-OMeTPA based perovskite solar cell device achieved a 13.8% energy conversion efficiency, which is significantly higher than that of Ge-OMeTPA based device.Chapter 7:carbazole based propeller-like compounds, namely H2CzB and H3CzB, are designed and synthesized. The different connection sites significantly affect the photophysical and electrochemical properties of the compounds. Their HOMO levels are-5.40 and-5.18 eV for H2CzB and H3CzB, respectively. Due to the highly distorted structure, H2CzB and H3CzB owned a large optical band gap of 3.28 and 3.36 eV, respectively. Space charge limiting current method evaluated their hole mobility as 1.98 ×10-5cm2V1 s-1 for H2CzB and 1.89×10-6 cm2V-1 s-1 for H3CzB, respectively, which indicates that H2CzB and Spiro-OMeTAD are potential hole transport material.Chapter 8:Three triarylboron-based thermally activated delayed fluorescence (TADF) emitters are designed and synthesized through integrating electron-donating (D) phenoxazine unit and electron-accepting (A) triarylboron unit. Owing to the higly twisted structures arising from the large steric hindrance of tetramethylphenyl group and the adjacent phenoxazine unit, the HOMOs and LUMOs of these molecules are well separated, resulting in small energy gaps (△EST) and effcient reverse intersystem crossing (RISC) process. The donor-acceptor ratio in these molecules significantly influence the rate constant of RISC (kRISC). By consecutively attaching an additional donor into the triarylboron core, a significant improved kRISC can be obtained. Moreover, the increasing phenoxazine units form a rigid structure, thereby it effectively suppresses the non-radiative decay process and renders a high photoluminescence quantum yield (PLQY). Employing these TADF emitters in solution-processed organic light-emitting diodes achieves a maximum external quantum efficiency of 13.9% and slight efficiency roll-off.更多还原