TY - JOUR
T1 - Thermally cross-linkable hole-transporting materials on conducting polymer
T2 - Synthesis, characterization, and applications for polymer light-emitting devices
AU - Cheng, Yen-Ju
AU - Liu, Michelle S.
AU - Zhang, Yong
AU - Niu, Yuhua
AU - Huang, Fei
AU - Ka, Jae Won
AU - Tian, Yanqing
AU - Jen, Alex K.Y.
PY - 2008/1/22
Y1 - 2008/1/22
N2 - A series of novel hole-transporting materials (HTMs) bearing thermally cross-linkable styryl groups have been synthesized and characterized. These HTMs could be in situ cross-linked under mild thermal polymerization without any initiator. The cross-linking temperatures (150-180 °C) for these HTMs are substantially lower than that typically used for curing perfluorocyclobutane (PFCB)-based HTMs (230 °C). After cross-linking, the resultant HTMs form robust, smooth, and solvent-resistant networks, which enables the subsequent spin-coating of emissive layer (EML). The HTMs based on an ether linkage connecting triarylamine dimers exhibited better hole-transporting ability compared to their corresponding monotriarylamine compounds due to higher content and closer distance of the hole-transporting units. Most importantly, the milder cross-linking condition for these HTMs allows the commonly used conducting polymer, poly(3,4-ethylenedioxythiophene): poly(4-styrenesulfonate) (PEDOT:PSS), to be incorporated as the bottom hole-injecting layer to improve turn-on voltage and power efficiency of the devices. This PEDOT/HTM double-layer hole-injecting/hole-transporting configuration also provides the combined advantages of preventing acidic PEDOT:PSS-induced quenching of emission, facilitating cascade hole injection and transport, and functioning as an efficient electron blocker. One of the devices that combines 2-NPD with PEDOT:PSS showed much improved performance of low turn-on voltage (3.3 V), high luminous efficiency (10.8 cd/A), and brightness (21 500 cd/m2).
AB - A series of novel hole-transporting materials (HTMs) bearing thermally cross-linkable styryl groups have been synthesized and characterized. These HTMs could be in situ cross-linked under mild thermal polymerization without any initiator. The cross-linking temperatures (150-180 °C) for these HTMs are substantially lower than that typically used for curing perfluorocyclobutane (PFCB)-based HTMs (230 °C). After cross-linking, the resultant HTMs form robust, smooth, and solvent-resistant networks, which enables the subsequent spin-coating of emissive layer (EML). The HTMs based on an ether linkage connecting triarylamine dimers exhibited better hole-transporting ability compared to their corresponding monotriarylamine compounds due to higher content and closer distance of the hole-transporting units. Most importantly, the milder cross-linking condition for these HTMs allows the commonly used conducting polymer, poly(3,4-ethylenedioxythiophene): poly(4-styrenesulfonate) (PEDOT:PSS), to be incorporated as the bottom hole-injecting layer to improve turn-on voltage and power efficiency of the devices. This PEDOT/HTM double-layer hole-injecting/hole-transporting configuration also provides the combined advantages of preventing acidic PEDOT:PSS-induced quenching of emission, facilitating cascade hole injection and transport, and functioning as an efficient electron blocker. One of the devices that combines 2-NPD with PEDOT:PSS showed much improved performance of low turn-on voltage (3.3 V), high luminous efficiency (10.8 cd/A), and brightness (21 500 cd/m2).
UR - http://www.scopus.com/inward/record.url?scp=38949093531&partnerID=8YFLogxK
U2 - 10.1021/cm071828o
DO - 10.1021/cm071828o
M3 - Article
AN - SCOPUS:38949093531
SN - 0897-4756
VL - 20
SP - 413
EP - 422
JO - Chemistry of Materials
JF - Chemistry of Materials
IS - 2
ER -