Highly efficient inverted organic light-emitting diodes with organic p-n junction as electron injection layer
Chuan Zhang, Xianfeng Qiao, Zhenlin Yang, Hongmei Zhang, Dongge Ma
Index: 10.1016/j.orgel.2018.03.047
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Abstract
Organic p-n junction (PNJ) composing of PEDOT:PSS(MoO3)/Bphen:Cs2CO3 is introduced as electron injection layer (EIL) in the bottom-emission inverted organic light-emitting diodes (BIOLEDs). The devices with PNJ of PEDOT:PSS/Bphen:Cs2CO3 or MoO3/Bphen:Cs2CO3 as EIL achieve maximum current efficiency of 87.3 cd/A and 86.6 cd/A and power efficiency of 69.4 lm/W and 63 lm/W, respectively, which are higher than that79.8 cd/A and 60 lm/W of the device with the n-doping Bphen:Cs2CO3 as EIL, and 51% and 55% improvement in the half operational lifetime. The injection of electrons from the interface of PNJ but not directly from the ITO cathode is more effectively comparison with conventional BIOLED with n-doped Bphen:Cs2CO3 as EIL. Thus, reducing the charge accumulation between the electrode and the organic electron transport layer (ETL), moreover, the PNJ is able to control the injection equilibrium of the carriers, and improve the efficiency and stability of the device.