Synthesis of Poly(phenylenesulfidephenyleneamine) Derivatives for the Applications of PLED Devices

• Main Authors: Chieh-Hsiu Hsieh, 謝杰修
• Other Authors: Chain-Shu Hsu
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/58496691787299844835

碩士 === 國立交通大學 === 應用化學系所 === 93 === In this study, four kinds of novel nitrogen- and sulfur-containing conjugated polymers, i.e., poly(phenylenesulfidephenyleneamine), poly (phenylenesulfide-alt-phenyleneaminephenyleneamine), poly(phenylene- sulfide-alt-N-(4-phenoxybutylphosphonic acid) phenyleneamine), and poly(phenylenesulfide-alt-N-(n-butylphosphonic acid) phenyleneamine) (P1∼P4), were synthesized via a CF3SO3H-induced polycondensation. The polymer P1 shows the highest molecular weight. Its number-average molecular weight is as high as 1.7 × 105. The polymer P2 shows the lowest molecular weight. Its number-average molecular weight is only 8 × 103. The reason could be due to the monomer M2 containing two phenylamine units which result in decreasing the electron density of the nucleophile and lowering the nucleophilicity to attack the sulfur cation during polymerization. All four polymers are soluble in common solvents, such as THF, DMF, and DMSO. Polymers P1-P4 show glass transition temperatures (Tg) ranging from 83 to 140℃ and thermal decomposition temperatures (Td) ranging from 240 to 400℃. Both P3 and P4 exhibit much lower Td and Tg than those of P1 and P2. The reason could be due to the incorporation of the long alkyl side groups in the main chains. The electrochemical properties of these four polymers were measured by cyclic voltammetry. The energy values of highest occupied molecular orbital (HOMO) are in the range from -4.82 to -5.07 eV. It means these polymers can be used as hole-transport layers (HTL) in two-layer polymer light-emitting devices (PLEDs) with the configuration of ITO/HTL/light emitting polymers/Ca/Al. The light emitting polymers are DP-PPV or polyfluorene derivatives. By adding camphor sulfonic acid (CSA) into the HTL as dopant, the current density, brightness and efficiency of the PLED devices can be extremely enhanced. Three kinds of devices are fabricated with different HTLs: (a) PPSA derivatives (P1~P4); (b) PEDOT; (c) PPSA derivatives and PEDOT. The results demonstrate that the (c) series of devices which use both PPSA derivatives and PEDOT layers show much better performance than the others. The maximum brightness of a green device using PPSA derivatives and PEDOT as HTL and DP-PPV derivatives as emitting layer is 3542 cd/m2 at 10 V. The best efficiency (0.95 cd/A) is shown by a blue device using PPSA derivatives and PEDOT as HTL and polyfluorene as emitting layer.