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基于酞菁的有机近红外发光器件与太阳能电池
Organic Near-infrared Light-emitting Devices and Solar Cells Based on Phthalocyanines
【作者】 范昭奇;
【导师】 杜国同;
【作者基本信息】 大连理工大学 , 微电子学与固体电子学, 2010, 博士
【摘要】 当今时代是信息化时代,随着信息产业化逐步从微电子时代过渡到光电子时代和光子时代,光电材料将成为光电产业的基础支撑。有机半导体光电材料不但具有低毒、价廉、易成型、柔性等优点,还具有光电响应快的特性,有可能在分子尺寸实现对电子行为的控制,并制成分子器件,这就有可能克服无机材料集成电路的集成度限制所带来的困难。酞菁是一类重要的有机小分子光电功能材料,具有大的共轭性和显著的半导体特性,在有机近红外电致发光器件和有机太阳能电池的制备中发挥着重要的作用。本文研究了无取代氢酞菁H2Pc的光学性质,然后将H2Pc掺入Alq3作为发光层采用真空蒸镀法制备了有机近红外电致发光器件。研究了H2Pc浓度对器件电致发光谱的影响,708 nm和800 nm附近的发射峰是在H2Pc浓度低时出现,而910 nm和930 nm附近的发射峰是在H2Pc浓度高时出现,详细讨论了这些发射峰来源,并分析了器件发光机制。合成了四取代氢酞菁Tetra-H2Pc,研究了其光学性质,并以Tetra-H2Pc为发光材料采用旋涂和真空蒸镀法制备了有机近红外电致发光器件。对比了Tetra-H2Pc和H2Pc发光性能,结果表明Tetra-H2Pc发光性能较好,还可通过旋涂方法成膜,简化器件工艺。以十六氟铜酞菁CuPcF16为发光材料制备了发射波长在1106 nm附近的有机近红外电致磷光器件。器件结构包括单层结构和多层掺杂结构,发光层主体材料分别采用了Alq3、CBP和TPBI,研究表明TPBI是一种较好的主体材料。详细讨论了以TPBI为发光层主体材料的器件的发光机制,并通过在发光层后面插入Alq3:DCJTB层提高了器件发光强度。合成了四取代铜酞菁(4-tert)CuPc,研究了其光学性质,并以其为发光材料制备了发射波长在1110 nm附近的有机近红外电致磷光器件,优化了器件结构。CuPcF16和(4-tert)CuPc发射波长较长,发射光谱较宽,在光通信领域有着潜在的应用价值。以(4-tert)CuPc为电子给体材料制备了单层结构、双异质结、本体异质结和具有周期性结构的有机太阳能电池。对器件进行了优化,并分析了器件的光电性能,研究表明所有器件都有明显的光伏效应。(4-tert)CuPc的吸收谱与常用的电子受体材料C60吸收谱互补,其能级与C60能级匹配也好,因此作为一种新颖的给体材料可用于制备各种结构的有机太阳能电池,又由于其溶解性较好,有望通过旋涂方法来简化器件制备工艺。研究了氟化镱YbF3作为阴极修饰层对基于CuPc的有机聚合物太阳能电池光伏性能的影响,结果表明YbF3层的插入可以提高器件的开路电压、填充因子和能量转换效率。讨论了YbF3层的作用机制。
【Abstract】 The present age is an information age. With the gradual transition of information industrialization from microelectronic age to optoelectronic age, the optoelectronic materials will become the basic support of optoelectronic industry. Organic semiconductor optoelectronic materials have many advantages, such as low toxicity, low cost, easy forming and flexibility. They also have the characteristic of fast optoelectronic response. The electron behavior can be controlled in the molecular size by using these materials, which makes it possible to produce molecular devices. This makes it possible to overcome the difficulty caused by the limitation of integration level of integrated circuit based on inorganic materials. Phthalocyanine is an important kind of organic small molecules-based photoelectric functional material, which has large conjugacy and remarkable characteristic of the semiconductor. They play an important role in making near-infrared organic light emitting devices (NIR-OLEDs) and organic solar cells (OSCs).In this thesis, the optical properties of metal-free phthalocyanine (H2Pc) are investigated. NIR-OLEDs were fabricated based on H2Pc doped into Alq3 The organic layers and metal electrode were deposited by vacuum thermal evaporation. The effect of H2Pc doping concentration on the electroluminescence (EL) spectra was investigated. The results indicated that the emissions around 708 nm and 800 nm appeared at low concentration, while the emissions around 910 nm and 930 nm appeared at high concentrations. We discussed the origins of these emissions in details and analyzed the luminous mechanism of the device. Tetra (2-Isopropyl-5-methylphenoxyl) substituted metal-free phthalocyanine (Tetra-H2Pc) was synthesized and its optical properties were also investigated. NIR-OLEDs were fabricated based on Tetra-H2Pc. The devices were fabricated by vacuum deposition and spin coating methods. The EL intensity at about 910 nm in the devices based on Tetra-H2Pc was increased by about 14 times compared with the intensity at about 930 nm in the devices based on H2Pc. This indicated that Tetra-H2Pc was a better kind of luminous material. The preparation technology of the devices can also be simplified because the films can be deposited by spin coating.NIR-OLEDs were fabricated by employing CuPcF16 as phosphorescent emitter. The devices emitted light around 1106 nm. The device structures included single-layer and multi-layer structures. Alq3, CBP and TPBI were employed as the host material in the light-emitting layer respectively. The result indicated that TPBI was a better host material. The luminescence mechanism of the device employing TPBI as host material was discussed in details. The luminescence intensity of the device-TPBI was enhanced by inserting Alq3:DCJTB layer below the light-emitting layer. (4-tert)CuPc was synthesized and its optical properties were also investigated. NIR-OLEDs were fabricated employing (4-tert)CuPc as phosphorescent emitter and the device structures were optimized. The device emitted light around 1110 nm. The emission wavelengths of CuPcF16 and (4-tert)CuPc were long. Their emission spectra were also wide. So they have potential applications in optical communication.OSCs were fabricated by employing (4-tert)CuPc as donor. The device structures included single-layer structure, double-heterostructure, bulk-heterostructure and periodic structure. The devices were optimized and the photoelectric performances of the devices were also analyzed. The investigation indicated that all the devices had the remarkable photovoltaic effect. The absorption spectrum of (4-tert)CuPc was complementary to that of C60 which was a common donor. The highest occupied molecular orbital and lowest unoccupied molecular orbital of (4-tert)CuPc matched well with those of C60.So as a novel donor, (4-tert)CuPc can be used to fabricate many types of OSCs. The preparation technology of the devices based on (4-tert)CuPc can possibly be simplified because (4-tert)CuPc has good solubility, which makes it possible to prepare (4-tert)CuPc films by spin coating.The influences of YbW3 on the photovoltaic performances of organic polymer solar cells based on CuPc were investigated. YbF3 was used as cathode modification layer in the device. The result indicated that the open circuit voltage, short circuit current and fill factor were enhanced after the insertion of YbF3 layer. The functional mechanisms of YbF3 were also analyzed through ultraviolet photoelectron spectroscopy.
【Key words】 Phthalocyanine; Organic light-emitting devices; Near-infrared; Organic solar cells;