Thermally cross-linkable hyperbranched polymers containing triphenylamine moieties: Synthesis, curing and application in light-emitting diodes

• Published in: Polymer (Guilford) Vol. 51; no. 20; pp. 4484 - 4492
• Main Authors: Yu, Juin-Meng, Chen, Yun
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 17.09.2010; Elsevier
• Subjects: Applied sciences; Crosslinking; Curing; Differential scanning calorimetry; Electronics; Exact sciences and technology; Hyperbranched polymers; Light-emitting diodes; Luminance; Multilayers; Optoelectronic devices; Organic polymers; Physicochemistry of polymers; Polymers with particular properties; Preparation, kinetics, thermodynamics, mechanism and catalysts; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Synthesis; Terminals; Thermally cross-linkable; Triphenylamine; Triphenylamine; Thermally cross-linkable; Hyperbranched polymers; Solution polycondensation; Brightness; Photoluminescence; Heck reaction; Electroluminescence; Branched copolymer; Curing (plastics); Experimental study; Thermosetting resin; Crosslinked copolymer; Electrochemical properties; Conjugated copolymer; Optical properties; Preparation; Hyperbranched copolymer; Organic light emitting diodes; Chemical reactivity; Fluorene derivative copolymer; Phenylenevinylene copolymer; Optical absorption
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/j.polymer.2010.08.001

This paper demonstrates synthesis of hyperbranched polymers ( HTP and HTPOCH 3 ), containing triphenylamine moieties in main chain and thermally cross-linkable periphery or terminal vinyl groups, and application as hole-transporting layer (HTL) in multilayer light-emitting diodes. Absorption and photoluminescence (PL) spectroscopy, cyclic voltammetry (CV) and differential scanning calorimetry (DSC) were employed to investigate their photophysical, electrochemical properties and thermal curing behaviors, respectively. The hyperbranched HTP and HTPOCH 3 were readily cross-linked by heating scan, with the exothermic peaks being at 221 and 210 °C respectively. The glass-transition temperatures ( T g ) of the hyperbranched polymers were higher than 140 °C after thermal cross-linking at 210 °C for 30 min. Multilayer light-emitting diodes (ITO/PEDOT:PSS/HTL/MEH-PPV/Ca/Al), using HTP and HTPOCH 3 as HTL, were readily fabricated by successive spin-coating. The performance of MEH-PPV device (maximum luminance: 9310 cd/m 2, luminance efficiency: 0.26 cd/A) was effectively enhanced by inserting the thermally cross-linked HTP or HTPOCH 3 as HTL ( HTP: 12610 cd/m 2, 0.32 cd/A; HTPOCH 3 : 14060 cd/m 2, 0.33 cd/A). This indicates that these thermally cross-linkable hyperbranched HTP and HTPOCH 3 are very suitable for the fabrication of multilayer PLEDs using solution processes. [Display omitted]