spectrum compares well with the photoluminescence pl spectrum of compound 1 fig7 indicating that both el and pl arise from the same excited state or the same type of exciton which is attributed to the excimeric intraligand emission resulting from the u03c0 stacking of the c n c ligand fig1 c and 11d show the characteristics of device 2 with the relationship between current density luminance and voltage and between current power efficiency and current density the turn on voltage is about 5 v fig1 a shows an illustrative oled structure of device 3 ito tpd 70 nm compound 8 30 nm 2 9 dimethyl 4 7 diphenyl 1 10 phenathroline bcp 30 nm alq 3 10 nm lif 0 6 nm al 150 nm bcp acts as the hole blocking material the electroluminescence spectrum of device 3 is depicted in fig1 b the el spectrum shows only one band at around 580 nm the el spectrum compares well with the photoluminescence pl spectrum of compound 8 shown in fig5 indicating that both el and pl arise from the same excited state or the same type of exciton which is attributed to the excimeric intraligand emission resulting from the 7 stacking of the c n c ligand fig1 c and 12d show the characteristics of device 3 with the relationship between current density luminance and voltage and between current power efficiency and current density the turn on voltage is about 6.