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Enhanced charge generation in doped organic/organic p–n heterojunction for improving the performance of tandem organic light emitting diode
Author(s) -
Qin Dashan,
Zhao Wei,
Chen Li,
Shi Zhihua,
Cao Huan
Publication year - 2017
Publication title -
journal of the society for information display
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.578
H-Index - 52
eISSN - 1938-3657
pISSN - 1071-0922
DOI - 10.1002/jsid.557
Subject(s) - homo/lumo , biphenyl , tandem , materials science , heterojunction , doping , oled , analytical chemistry (journal) , chemistry , molecule , optoelectronics , nanotechnology , organic chemistry , layer (electronics) , composite material
The doped organic/organic p–n heterojunctions have been applied as charge generation structure (CGS) in tandem organic light emitting diodes (TOLEDs). It is found that the field‐induced charge generation takes place more efficiently at the interface between Li 2 CO 3 n‐doped bathocuproine (BCP:Li 2 CO 3 ) and MoO 3 p‐doped 4,4′‐ N , N′ ‐dicarbazole‐biphenyl (CBP:MoO 3 ) than at the interface between BCP:Li 2 CO 3 and MoO 3 p‐doped 4,4‐bis[ N ‐1‐naphthyl‐ N ‐phenylamino]biphenyl (NPB:MoO 3 ). It is because the process of electrons tunneling through the depletion zone from the highest occupied molecular orbit (HOMO) of CBP:MoO 3 to the lowest unoccupied molecular orbit (LUMO) of BCP:Li 2 CO 3 is more efficient than that from the HOMO of NPB:MoO 3 to the LUMO of BCP:Li 2 CO 3 . Compared to the TOLED using the conventional CGS of 10‐nm BCP:Li 2 CO 3 /20‐nm NPB:MoO 3 , the one using the CGS of 10‐nm BCP:Li 2 CO 3 /10‐nm CBP:MoO 3 /10‐nm NPB:MoO 3 shows increased device performance. In addition, the interconnecting property of CGS of 10‐nm BCP:Li 2 CO 3 / x nm CBP:MoO 3 /20 − x nm NPB:MoO 3 shows a strong dependence on the thickness of CBP:MoO 3 . We provide a new insight on optimizing Ohmic loss in the CGSs, useful for improving the performance of TOLEDs.