本文選題：有機電致發(fā)光　切入點：有機中性自由基　出處：《吉林大學(xué)》2017年博士論文　論文類型：學(xué)位論文

【摘要】：在顯示和照明領(lǐng)域中,有機電致發(fā)光器件(OLED)的應(yīng)用是一件開創(chuàng)性的工作,OLED器件集成了自發(fā)光、全視角、可彎曲、能耗低等諸多優(yōu)勢,逐漸成為顯示和照明領(lǐng)域的領(lǐng)跑者。然而,有機電致發(fā)光器件的研究仍然存在一些關(guān)鍵性問題。比如,如何在降低材料成本的同時又有效利用不發(fā)光的三線態(tài)激子等。雖然磷光材料能夠有效地解決熒光OLED中三線態(tài)激子利用難的問題,從而實現(xiàn)100%器件內(nèi)量子效率(IQE),但是貴重金屬的磷光材料價格昂貴,并且難以獲得能夠達(dá)到歐洲廣播聯(lián)盟(EBU)標(biāo)準(zhǔn)的深藍(lán)磷光材料。最近,熱致延遲熒光(TADF)材料解決了OLED材料價格昂貴的問題,實現(xiàn)了熒光分子中三線態(tài)激子的有效利用,從而獲得了IQE為100%的OLED器件。除此之外,研究報道顯示,通過三線態(tài)-三線態(tài)淬滅(TTA)和雜化局域電荷轉(zhuǎn)移激發(fā)(HLCT)態(tài)等途徑也可以有效利用三線態(tài)激子實現(xiàn)高效率發(fā)光。雖然上述方法具備的優(yōu)點進(jìn)一步推進(jìn)了OLED的發(fā)展,但是存在的一些問題仍需要我們繼續(xù)探索,以獲得廉價、高效率的材料與器件。因此,本論文討論了OLED的發(fā)展?fàn)顩r、工作原理、不同類型OLED發(fā)光材料及其發(fā)光原理和優(yōu)缺點。為了解決三線態(tài)激子難以利用和材料價格昂貴等問題,與其他發(fā)光機理不同,我們提出了有機中性自由基雙重態(tài)發(fā)光機理。從發(fā)光機理來看,磷光、TADF、TTA或者HLCT,都圍繞著“三線態(tài)激子利用”的問題展開研究。與上述工作都不同,本論文中提出了雙重態(tài)發(fā)光原理。由于有機中性自由基(有機開殼分子)分子最外層只有一個單電子,根據(jù)量子力學(xué)原理,單個未成對電子的自旋組態(tài)為雙重態(tài)。這種雙重態(tài)激子躍遷返回基態(tài)時,不會受到電子自旋禁阻的限制。因此,理論上以有機開殼發(fā)光分子作為發(fā)光材料的OLED器件內(nèi)量子效率能夠達(dá)到100%。因此,我們以研究有機中性自由基雙重態(tài)激子發(fā)光機理為目標(biāo),重點進(jìn)行了以下幾方面的工作:1.我們選擇穩(wěn)定且發(fā)光的三(2,4,6-三氯苯基)甲基自由基(TTM),根據(jù)相關(guān)文獻(xiàn)報道適當(dāng)優(yōu)化反應(yīng)條件,通過與咔唑反應(yīng),成功合成出對應(yīng)的中性自由基TTM-1Cz和TTM-2Cz。兩類自由基均表現(xiàn)出良好的熱穩(wěn)定性(熱分解溫度均在330℃以上)和較高的發(fā)光效率。其中TTM-1Cz和TTM-2Cz在正己烷溶液中的發(fā)射峰分別位于628 nm和640 nm,處于深紅光區(qū),熒光量子效率分別為53%和54%。研究其光物理性能發(fā)現(xiàn),三種自由基的發(fā)光都來自于雙重態(tài),不同之處是TTM的發(fā)光來自于局域態(tài),而TTM-1Cz和TTM-2Cz的發(fā)光來自于CT態(tài)的雙重態(tài)發(fā)光。光穩(wěn)定性實驗結(jié)果表明TTM、TTM-1Cz和TTM-2Cz的半衰期分別為1.6×102 s、9.9×103 s和4.7×105 s,隨著咔唑數(shù)量增多穩(wěn)定性大幅提高。其次,我們以CBP作為母體,制備了摻雜濃度為5%的中性自由基發(fā)光OLED器件,TTM-1Cz和TTM-2Cz的摻雜器件的最大EQE效率分別達(dá)到2.4%和0.8%,EL譜峰值波長處于693 nm和690 nm。磁場效應(yīng)實驗結(jié)果進(jìn)一步證明器件的發(fā)光來自于雙重態(tài)發(fā)光。2.通過優(yōu)化自由基的器件結(jié)構(gòu),利用自由基和前體的混合物,初步實現(xiàn)了雙重態(tài)激子發(fā)光OLED器件,雙重態(tài)激子的生成比例(χD)接近于100%。為了進(jìn)一步研究混合物(前體和自由基)的性能和準(zhǔn)確調(diào)控自由基的摻雜比例,我們合成出TTM-1Cz和TTM-2Cz的前體(αHTTM-1Cz和αHTTM-2Cz)。通過研究其光物理性能發(fā)現(xiàn),自由基前體均為寬能隙且具有較低發(fā)光效率的閉殼分子。研究不同摻雜濃度的自由基TTM-1Cz和前體αHTTM-1Cz的OLED器件發(fā)現(xiàn),前體和自由基的摻雜不僅改善了自由基的聚集淬滅,而且提高了器件性能。其中TTM-1Cz自由基在前體中摻雜濃度為2.5%時器件EQE達(dá)到10.5%,EL光譜峰值波長為666 nm,是非磷光材料作為發(fā)光層的深紅光熒光器件中EQE的最高值。這種準(zhǔn)確調(diào)控自由基前體和自由基的主-客體摻雜方式,證明中性自由基發(fā)光的OLED器件內(nèi)量子效率上限能達(dá)到100%,并且是解決自由基聚集淬滅的新方案。3.為了研究影響自由基穩(wěn)定性和光物理性能的因素,我們通過在咔唑3,6位上引入缺電子基團苯甲�；透浑娮踊鶊F叔丁基,與自由基TTM反應(yīng)得到兩種新自由基TTM-1Cz Bz和TTM-1Czt B。兩種自由基都表現(xiàn)出較高的熱穩(wěn)定性(熱分解溫度均330℃),研究發(fā)現(xiàn),TTM-1Cz Bz和TTM-1Czt B在正己烷溶液中的發(fā)射峰分別在614 nm和640 nm處出現(xiàn),與TTM-1Cz相比分別藍(lán)移14 nm和紅移12nm,熒光量子效率分別為54%和55%。實驗結(jié)果表明:咔唑上缺、富電子基團的引入不僅影響自由基的光物理性能而且對自由基的光穩(wěn)定性具有很大的影響。與TTM-1Cz相比,TTM-1Cz Bz的光穩(wěn)定性降低15倍左右,而TTM-1Czt B的光穩(wěn)定性比TTM-1Cz高4.5倍以上。研究自由基器件單載流子遷移率發(fā)現(xiàn),缺電子基團苯甲�；沟米杂苫娮舆w移率提高,而給電子基團叔丁基導(dǎo)致器件空穴和電子遷移率均有所降低。最終,我們制備了以兩種自由基(TTM-1Cz Bz和TTM-1Czt B)作為發(fā)光客體5 wt.%摻雜于CBP中的OLED器件,最大外量子效率分別達(dá)到5.2%和2.8%。其中TTM-1Czt B摻雜器件的EL光譜峰值波長在745 nm。
[Abstract]:In the display and lighting in the field of organic electroluminescent devices (OLED) application is a pioneering work, the OLED device integrates self luminous, wide viewing angle, can be bent, the many advantages of low energy consumption, has become a leader in the field of display and lighting. However, there are still some key problems of electromechanical induced the light emitting device. For example, how to reduce the material cost and the effective use of no light of three excitons. Although phosphorescent materials can effectively solve the difficult problem of three excitons by fluorescence OLED, thus realizing the 100% device internal quantum efficiency (IQE), but the price of expensive precious metal phosphorescent materials it is difficult to obtain, and can reach the European Broadcasting Union (EBU) blue phosphorescent material standard. Recently, the heat induced delayed fluorescence (TADF) material to solve the problem of expensive OLED material, the fluorescent molecule three triplet excitation The effective use of the thus obtained IQE devices for 100% OLED. In addition, the research report shows that by three - three triplet triplet quenching (TTA) and hybrid local charge transfer excited state (HLCT) approach can also be effective use of three excitons to achieve high efficiency light. Although the advantages of the method with the further development of OLED, but some problems still need to continue to explore, to obtain cheap materials and devices with high efficiency. Therefore, this paper discusses the development status of OLED, the working principle of different types of OLED luminescent material and luminescent principle and advantages and disadvantages. In order to solve the problem of three excitons it is difficult to use and the materials are expensive, unlike other luminescence mechanism, we propose a light-emitting organic neutral radical doublet mechanism. From the light emitting mechanism, phosphorescence, TADF, TTA or HLCT, all around three triplet excitation Study on using "problem. Different from the above work, this paper proposes a dual state luminescence principle. Because the organic neutral radical (organic open shell molecules) the outermost molecular only a single electron, according to the principle of quantum mechanics, single unpaired spin group electronic states as a doublet. This dual state excitontransition return to the ground state, not by the electron spin forbidden limit. Therefore, the theory of open shell to organic light emitting molecule OLED devices as luminescent materials internal quantum efficiency can reach 100%. so we to study organic neutral radical double exciton luminescence mechanism as the goal, focus on the following aspects: 1. selection of stable and light (three 2,4,6- three chlorophenyl) methyl radical (TTM), the appropriate reaction condition optimization according to the related literature reports, with the successful synthesis of carbazole reaction, since the corresponding neutral By TTM-1Cz and TTM-2Cz. two kinds of free radicals showed good thermal stability (thermal decomposition temperature at 330 DEG C) and high luminous efficiency. The TTM-1Cz and TTM-2Cz emission peaks in hexane solution are located at 628 nm and 640 nm, in a deep red zone, the fluorescence quantum efficiency were 53% and the 54%. study found its photophysical properties, emitting three free radicals from the dual state, the difference is that TTM light from the local state, and the state of TTM-1Cz and TTM-2Cz dual luminescence from CT state light. Light stability of the experimental results showed that TTM, TTM-1Cz and TTM-2Cz has a half-life of 1.6 * 102 s respectively. 103, 9.9 * s and 4.7 * 105 s, with the increase in the number of carbazole stability to enhance largely. Secondly, we take CBP as the parent, was prepared by doping concentration of neutral radical 5% light emitting devices of OLED, maximum EQE and TTM-2Cz of the TTM-1Cz doped device The efficiency reached 2.4% and 0.8%, the peak wavelength of EL spectrum at 693 nm and 690 nm. from the experimental results further prove that the magnetic field effect devices emitting from dual state luminescence by.2. device structure optimization of free radicals, the use of a mixture of free radical and precursor, realized the double exciton luminescence of OLED devices, the proportion of double exciton generation the (x D) close to 100%. in order to further study the mixture (precursor and radical) doping ratio performance and accurate regulation of free radicals, we synthesized precursor TTM-1Cz and TTM-2Cz (HTTM-1Cz alpha and alpha HTTM-2Cz). Through the study of their photophysical properties found that free radical precursors are wide bandgap and it has low luminous efficiency of closed shell molecules. OLED devices of different doping concentration of free radicals and TTM-1Cz precursor alpha HTTM-1Cz, precursor and free radical doping not only improved the free radical quenching and aggregation. And improve the performance of the device. The TTM-1Cz free radicals in a precursor doping concentration of 2.5% EQE to 10.5% EL devices, peak wavelength is 666 nm, is non phosphorescent materials as the highest value of deep red fluorescence luminescence layer in EQE. The main object of the accurate control of radical doped precursors and free the proof of the neutral radical OLED light emitting device of the internal quantum efficiency limit can reach 100%, and is the new.3. solution free radical aggregation quenching in order to study the factors affecting the stability of free radicals and photophysical properties, we introduce a 3,6 carbazole by electron deficient groups and electron rich groups benzoyl tert butyl TTM, and free radical reaction of two new TTM-1Cz Bz and TTM-1Czt B. free radical two free radicals exhibit high thermal stability (thermal decomposition temperature of 330 DEG C), the study found that TTM-1Cz Bz and TTM-1Czt B in n-hexane The emission peak of dodecane solution respectively in 614 nm and 640 nm, respectively, compared with TTM-1Cz nm and a blue shift of 14 12NM red shift in fluorescence quantum efficiency was 54% and 55%. respectively. The experimental results show that the lack of carbazole and light physical properties, introducing electron rich groups not only influence the free radical with light stability of free radicals the great influence. Compared with TTM-1Cz, TTM-1Cz light stability of Bz is reduced by 15 times, and the light stability of TTM-1Czt B is higher than TTM-1Cz more than 4.5 times. On the free radical component of single carrier mobility, electron deficient unit benzoyl radical makes the electron mobility increases, while the electron donating tert butyl lead device the hole and electron mobility decreased. In the end, we were prepared with two kinds of free radicals (TTM-1Cz Bz and TTM-1Czt B) as a light emitting object 5 wt.% doped in CBP OLED device, the maximum external quantum efficiency respectively. The peak wavelength of EL spectra of TTM-1Czt B doped devices in 5.2% and 2.8%. is 745 nm.

【學(xué)位授予單位】：吉林大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2017
【分類號】：TN383.1;TQ422

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