【作者】 朱园园；

【导师】 刘燕刚；

【作者基本信息】 上海交通大学 ， 应用化学， 2011， 博士

【摘要】 酞菁类(Pc)和苝酰亚胺类(PDI)有机小分子半导体具有优良的光热稳定性,其分别作为空穴和电子传导材料,在现代有机光电功能器件的应用中具有重要作用。但从目前的研究来看,制约其应用发展的主要因素是:刚性分子结构导致的难溶解性;低成本且简单易控的成膜方法的欠缺;体系中光物理过程研究的不成熟性。本论文针对这些问题主要研究了如下内容:(1)合成了电子给体-受体(D-A)结构的三苯胺(TPA)类空穴传导材料,4,7-二(4-三苯胺基)-2,1,3-苯并噻二唑(TBT),研究了其与三氟乙酸(TFA)的质子化反应,并提出了质子化-电沉积法(PED)的TBT薄膜制备方法,探讨了成膜机理。制得的薄膜由直径可控(20~200 nm)的纳米球紧密排列组成。与旋涂法得到的TBT薄膜相比,PED法制备的薄膜不仅具有较高的结晶度,而且还具有相对较窄的带隙,表明该法可以得到良好空穴传导性质的TPA类结晶薄膜。(2)在-0.4 ~ -3.0 V的低电压范围内和低的TFA相对含量条件下,利用PED法制备得到了形貌可控的纳米线、纳米棒及微米带结构的CuPc薄膜。发现在70℃的沉积温度下CuPc能够形成规整的超长纳米线,进而研究了这种超长纳米线的形成过程。(3)利用质子化-共电沉积(PCD)的方法制备了TBT:CuPc的本体异质结薄膜。在此共电沉积的过程中,TBT与CuPc影响了彼此的结晶行为。复合薄膜形貌受组分相对含量及沉积时间控制。从TBT的相对摩尔百分含量(TBT%)为70%的TBT:CuPc混合溶液中沉积得到的复合薄膜具有纳米线与纳米球的双连续互穿网络结构。根据薄膜的吸收和发射光谱以及分子能级的匹配性,推测在TBT/CuPc异质结界面能够发生分子间能量和光诱导电荷转移,后者可由从TBT%=50%和70%的TBT:CuPc混合溶液中得到的复合薄膜存在强的表面光电压(SPV)增强效应得到证明。(4)研究了N,N’-二(4-甲氧基苄基)-3,4,9,10-苝四羧酸酰亚胺(PDI-32)和N,N’-二(4-乙氧基苯基)-3,4,9,10-苝四羧酸酰亚胺(PDI-123)这两种PDI衍生物与水合肼(HZH)的还原反应,并在此基础上分别利用阴离子自由基-电沉积法(AED)和阴离子自由基-共电沉积法(ACD)制备得到了两种PDI的单一和共混复合薄膜。AED薄膜形貌及分子聚集态受DMF溶液中PDI溶解程度大小影响,而此溶解程度除了与HZH加入量有关外,还受体系存放时间的影响。另外,薄膜的SPV性质表明,PDI-123的纳米颗粒薄膜由于其纳米粒子的表面态及表面O2吸收作用,使得其较PDI-32的纳米带/棒薄膜具有更强的光电压响应。PDI-32:PDI-123复合薄膜在600~700 nm和330~425 nm的吸收带均呈现出光电压增强效应,前者归因于PDI-123纳米粒子的表面态和表面吸附作用使与之相邻的PDI-32分子中的光生激子解离效率提高,而后者为这种表面态和表面吸附与分子间的光诱导电荷转移共同作用的结果。(5)基于对TBT和CuPc的PED,及PDI的AED薄膜制备方法的研究,采用逐层电沉积法制备了p/n型的双层异质结薄膜: TBT/PDI-32, TBT/PDI-123, CuPc/PDI-32,CuPc/PDI-123,TBT:CuPc/PDI-32和CuPc/PDI-32:PDI-123。此类双层膜中呈现的SPV增强效应说明在异质结界面存在分子间的光诱导电荷转移作用。且此电荷转移作用对不同类型的光生激子的解离具有不同的影响方式,导致双层膜之间的SPV增强效应具有互补性。另外,对于含有本体复合结构的双层膜,既存在单一双层膜中的界面效应,又存在其本体复合体系中的光电压增强效应。本论文不仅为TPA、Pc及PDI类有机小分提供了操作简单、可控性强的单一和复合薄膜的制备方法,而且利用SPV技术对此类光电功能薄膜中的不同类型光生激子的解离机制进行了研究。本论文为这类小分子半导体在有机光电器件中的应用提供了理论依据和研究基础。更多还原

【Abstract】 Derivatives of phthalocyanine (Pc) and perylene diimide (PDI) as excellent organic semiconductors, have been studied extensively in the organic photoelectric devices. But there still are some obstacles to their applications, such as low solubility, lack of simple and controllable film formation method, and immature theory of the photoelectrical transformation. In this dissertation, the research progresses on these organic semiconductors are summarized firstly. On the base of these, the film formation methods to them and the photoelectrical properties of their films are studied as follows:(1) The electron donor-acceptor (D-A) molecules, 4,7-bis(4-triphenylamino)benzo- 2,1,3-thiadiazole (TBT), is synthesized via Stille cross-coupling reaction. And the nanocrystalline films of TBT have been firstly formed by a facile protonation- electrodeposition (PED) method from the nitromethane solution of protonated TBT, in which trifluoroacetic acid (TFA) is used as the protonation reagents. The films are composed of nanospheres which diameters are controllable from 20 to 200 nm. Compared with the spin-coating films, PED films possess higher degree crystallization and lower band gap, with respect to superior intermolecular charge-transfer ability and more excellent hole-transporting property.(2) Films composed of various nanostructured copper phthalocyanine (CuPc) are controllably prepared by the method of PED, under the low voltage and the small molar ratio of TFA to CuPc. The ultralong nanowires of CuPc are grown at a high deposition temperature of 70℃.(3) The composite films of TBT:CuPc are fabricated via protonation-coelectro- deposition (PCD) from the nitromethane solutions of the TBT:CuPc mixture in the presence of TFA. The crystallization behavior of the two components is interacted by each other. Furthermore, the morphology of the composite films are controlled by relative content and codeposition time. The nanosphere-nanowire interpenetrating network structured films are obtained when the molar percentage of TBT being 70% in the precursor solutions. Based on the absorption and emission spectra as well as the match of molecular energy, there theoretically exists energy/charge transfer at the interface of TBT/CuPc heterojunctions. And the deduction of the charge transfer is proven by the obvious enhanced effect of the surface photovoltage (SPV) in the composite films which codeposited from the TBT:CuPc blending solutions of 50% and 70%TBT, respectively.(4) The reduction reactions of the two PDI derivatives, N,N’-di(4-methoxybenzyl)- 3,4,9,10-perylene diimide (PDI-32) and N,N’-di(4-ethoxyphenyl)-3,4,9,10-perylene diimide (PDI-123), with hydrazine hydrate (HZH), are thoroughly studied in the DMF solutions, respectively. On the base of this, the single-component and blending composite films of the two PDI are fabricated from the anionic radicals-contained solutions via anionic radical-electrodeposition (AED) and anionic radical-coelectrodeposition (ACD), respectively. The morphology of the AED films is controlled by the dissolving of PDI followed with the reduction reactions. And the dissolving is not only influenced by the content of HZH, but also dependent on the storing time. The surface photovoltage spectra (SPS) of the two single-component films indicate that, PDI-123 film composed of nanoparticles present stronger photovoltage response than the nanobelt/rod-composed PDI-32 films, due to the surface states and absorption of O2 on the PDI-123 nanoparticels. The SPS of the PDI-32:PDI-123 composite films show the SPV enhanced effect at the two absorption bands of 600~700 nm and 330~425 nm, respectively. And the former one is ascribed to the surface states and absorption of O2 on the PDI-123 nanoparticles, which make the photoinduced excitons in the neighbouring PDI-32 molecules be dissociated effectively, the later one is attributed to the coactions of the mentioned surface effect and the intermolecular charge transfer on the PDI-32/PDI-123 interface.(5) Based on the film formation methods of PED and AED, the p/n-type double-layer heterojunction composite films of TBT/PDI-32, TBT/PDI-123, CuPc/PDI-32, CuPc/PDI- 123,TBT:CuPc/PDI-32 and CuPc/PDI-32:PDI-123, are fabricated by means of layer-by- layer electrodeposition. The SPV enhanced effect presented in these double-layer films indicates that there exist the photoinduced intermolecular charge transfer at the heterojunction interface. And also, this charge transfer possesses different influence on the different type of exciton dissociation, which induces the complementarity of the SPV enhanced effect among various films. In addition, the double-layer films containing the bulk blending layer, not only show the interface effect in the simple double systems, but also present the photovoltage enhancement in the bulk composite films.This dissertation provides the flexible and controllable film formation methods for the derivatives of TPA, Pc and PDI, and obtained their composite films with SPV enhanced effect. Meanwhile, the dissociation mechanism of the different type of photoinduced exciton in the films is studied by SPV technology. This work provides abundant experiment data which will be significant for the fabrication of photoelectrical devices based on these derivatives.更多还原