On the origin of efficient electron injection at phosphonate-functionalized polyfluorene/aluminum interface in efficient polymer light-emitting diodes

Baohua Zhang; Chuanjiang Qin; Xiaodi Niu; Zhiyuan Xie; Yanxiang Cheng; Lixiang Wang; Xinglin Li
July 2010
Applied Physics Letters;7/26/2010, Vol. 97 Issue 4, p043506
Academic Journal
Ultraviolet and x-ray photoelectron spectroscopy are used to explore the underlying mechanism of efficient electron injection at phosphonate-functionalized polyfluorene (PF-EP)/Al interface in polymer light-emitting diodes (PLEDs). It is proposed that both the favorable interfacial dipoles of phosphonate groups and intense coordination interaction between the phosphonate groups and Al at PF-EP/Al interface are responsible for the efficient electron injection. As a result, the PLEDs with PF-EP/Al cathode demonstrate superior performance compared to the PLEDs with Ba or Ca cathode due to efficient electron injection and suppressed exciton-quenching at cathode interface.


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