| Multi-armed structure of donor-acceptor organic photoelectrical materials, because of their unusual molecular structures and opto-electronic properties, have been successfully used in many optoelectronic devices, such as organic light emitting diodes, organic photovoltaics, organic memory devices and so on. The Donor and Acceptor molecules may occur between the energy transfer and photoinduced electron transfer, and by changing the donor or the receptor structure and connections to adjust molecular spectra and energy level; Multi-armed structure of organic photoelectrical materials may prevent the formation of molecular aggregation satae, as well as improve the amorphous stability and solubility of the material, soluble in common organic solvents such as chloroform. Through the following four ways which change the peripheral type of electron-donating group, arms conjugate length, the position of the alkyl group and the type of the central core, we changed the structure of donor and further Systematically investigated the performance of the Donor-Acceptor in photophysical, electrochemical and optical properties.Firstly, we synthesized a series of star-shaped molecules (P1, P2and P3), with truxene as the core, thiophene unit as donor, and benzothiadiazole chromophore as the acceptor. By spectroscopy and cyclic voltammetry method to study the changes in arms conjugate length in changing the position of the alkyl group and the number of alkyl thiophene group, due to the difference in ability to the electronic, molecular absorption and photoluminescence color impact and effect on the tuning of molecular energy levels. This series of molecules as emitting layer electroluminescent devices were prepared to obtain the relevant parameters of luminescent properties, and compare the relationship between them. The study found that P1and P2have orange emissive, but P3red emissive. OLEDs were fabricated using the following configuration:ITO/PEDOT:PSS (50nm)/EML (74nm)/TPBI (30nm)/LiF (1.3nm)/A1(80nm). For D2and D4, the devices displayed a maximum luminance of4683and4730cd/m2were found with an efficiency of0.50and2.50cd/A, respectively.Then, we designed and synthesized two linear molecules P4and P6, and two star-shaped molecules P5and P7with truxene as the core, thiophene and9-(4-phenyl)-9H-carbazole as donor, benzothiadiazole as the acceptor. Such p-n molecular design makes it possible to probe the relationship between the extension of donor chromophores and their corresponding photophysical and electrochemical properties. It is desirable to adjust energy level in changing molecular structure and the introduction of thiophene units. On the one hand, this series of materials as the light emitting layer was prepared OLED light emitting performance parameters, and find and compare the relationship between them. On the other hand, star-shaped molecules P5and P7as a function of the storage layer by spin coating method with organic memory device, both devices have shown good Flash features.Finally, we synthesized two efficient star-shaped white electroluminescent polymers, containing FCZTBTX with an orange emissive core and three blue light-emitting arms, and F(CZ)2FBTX with an orange emissive core and four blue light-emitting arms. By adjusting the content of the orange core, partial energy transfer and charge trapping from the blue arms to the orange core is realized and leads to emission from both the core and the arms. The photophysical, electrochemical properties of the polymers are analyzed. A single-layer device of FCZTBTX emits white light, With Lmax of737cd/m2and CIE coordinate of (0.35,0.39). |
