Improved Efficiency of Hybrid Inorganic-Organic Light Emitting Diodes

摘要

We report the synthesis and characterization, optical and optoelectronic properties of charge carrier materials, namely pristine ZnO, Ag-doped ZnO and Cu-Ag-codoped ZnO and their performance with iridium(III) bis-1-(4-methoxyphenyl)-2-(4-naphthalen-1-yl)-4,5-diphenyl-1H-imidazolato-N,C-2)( picolinate) as the emitter in green inorganic-organic hybrid light emitting devices (HyLEDs). The device with 2.0 wt Cu-Ag-codoped ZnO nanoparticles shows luminance of 11,842 cd/m(2) at driving voltage 15.0 V, 2.0 wt Ag-doped ZnO exhibits luminance of 10,982 cd/m(2) at 19.0 V and 2.0 wt ZnO shows luminance of 1431 cd/m(2) at 23.0 V. The device with Cu-Ag-codoped ZnO nano-particles layer shows higher current efficiency (eta(c)-15.4 cd A(-1)) and power efficiency (eta(p)-9.8 lm W-1) than those of the control devices eta(c)- 13.0 cd A(-1) (Ag-ZnO); 11.4 cd A(-1) (ZnO) eta(p)-8.4 lm W-1 (Ag-ZnO); 5.5 lm W-1 (ZnO). We have also fabricated the Cu-ZnO-MPNDI-Ag heterostructure in which Ag-MPNDI HIB is higher than the ZnO-MPNDI HIB and ZnO-MPNDI EIB is lower than Cu-ZnO-MPNDI EIB. Therefore electrons flow from Ag into the ZnO CB is possible until reaching the lowest energy state since ZnO has high electron mobility and hence Ag-to-MPNDIto-ZnO charge transfer direction is the dominant one.