Organic Near-infrared Light-emitting Devices And Solar Cells Based On Phthalocyanines

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.