Synthesis and Photoelectric Property of Tetra-aryloxy Phthalocyanines and Near-infrared Light-emitting Devices
|School||Dalian University of Technology|
|Course||Microelectronics and Solid State Electronics|
|Keywords||phthalocyanine synthesis electrochemistry near infrared light emitting|
Organic electronics is one hot point at present. In the past twenty years organic semiconductors have attracted much attention due to their unique characteristics. Organic semiconductor materials have a lot of merits such as wild varieties, easy molecular designing and modifying, simple device preparation process, low cost, conducting and luminescent abilities, photoconductive property, and easy fabricating large area devices. Organic semiconductors are the first choice for nano-electronic device and molecular electronic device. Organic semiconductors have been applied to fabricate all kinds of semiconductor devices. Organic semiconductor processes have been developed, which are different from the traditional inorganic processes.Phthalocyanines (Pcs) have unique two dimensional p conjugated electronic structure,18p electorons delocalized on nine C=N. Pcs’unique optoelectronic characteristics are originate from the effect of electronic delocalization. Strong p-p interaction occure among Pcs’conjugated macrocycles, which is the theoretical foundation for their unique optical, electrical and magnetic characterictics. Phthalocyanines have been investigated in fields such as non-linear optical, molecular electronic devices, electrochromic, liqued crystal diplayes, electroluminescence, solar cells and soncers.In this thesis22kinds of Pc are synthesized employing phenoxy, methoxy-phenoxy, biphenoxy, and4-methyl-2-tertary butyl, recpectively, as substituents. Photophysical properties, electrochemical properties are investigated. Some Pcs are used to fabricated near infrared electrluminescent devices.The influnces of the substituents’position, cntral metal ion and concentrations of solution on absorption and flunscence spectra are systerm investigated on Tetra-PPcs, Tetra-PPPcZn, Tetra-PPcZn, Tetra-MPPcZn, Tetra-PPPcZn and Tetra-MTBPPcZn. The results suggest that compared with the central ion, the substitution position has more effect on the absorption wavelength and the emission wavelength. Both the central ion and the substitution position have the dramatic effect on the fluorescent intensity. The central atom decreases the fluorescent intensity or quenches the fluorescence completely.Tetra-MPPcZn and Tetra-PPPcCo are investigated by electronchemical method, and the energy level are determined. Their cyclic voltammetric curves are recorded in chlorm solution10-3mol·L-1with scan rates of100mV·s-1. The first oxidation and first reduction processes occur on the Pc ring, and redox reactions should be quasi-reversible processes. Electrochemical reaction mechanisms are given. a-Tetra-PPPcCo’voltammetric curves is also obtained in DMF solution (10-3mol·L-1) with scan rates of50mV·s-1,100mV·s-1and200mV·s-1, respectively. The results suggest that the first oxidation and first reduction processes occur on cntral Co2+. With scan rate of50mV·s-1and100mV·s-1the first reduction process of Pc ring is single electron reversible processes, With scan rate of200mV·s-1the first reduction process of Pc ring is single electron quasi-reversible processes. Other oxidation and reduction process are all unreversible. The obtained paremeters vary little with different scan rates. With the increasing of scan rate EHOMO increase while ELOMO decrease.We fabricated organic light-emitting diodes (OLEDs) used a(B)-Tetra-PPcZn, a(β)-Tetra-MPPcZn, a-Tetra-MPPcH2and a-Tetra-PPPcZn, respectively, as emitters. Firstly, the photophysical properties of a-Tetra-MPPcH2are studied. The electroluminescent devices based on a-Tetra-MPPcH2are fabricated by vacum evaparation and spin coating, respectively. The influnce of doping concentration on performance of the device is investigaed. The results indicate that all the device have the emission around895nm, and the EL intensity first increased and then decrease with the increasing of the doping concentration. The optisim the concontration is40wt%. The EL mechnism is also dicussed. The NIR light-emitting devices based on a(B)-Tetra-MPPcZn and a-Tetra-PPcZn are prepared by spin coating. The influnce of the molecular structures on EL properties are disscused. Finaly, NIR EL around1470nm is realized by device based on a-Tetra-PPPcZn, which is near the window of the optical communication around1550nm.The EL devices in this thesis all exibit broad NIR emmission, and display the potential value on application to long wavelength optical communication.