A multiple organic light emitting device was fabricated with sub-monolayer technique, of which the structure is ITO/ m-MTDATA(50 nm)/C545T(0.05 nm)/DPVBi (d nm)/DCM2(0.05 nm)/Alq (60 nm)/LiF(1 nm)/Al. C545T and DCM2 sub-monolayer were inserted both the DPVBi sides. Effect of the thickness variation of DPVBi on the device performance was studied. As the thickness of DPVBi is 4 nm, the current efficiency is 4.19 cd/A at 4 V and the luminance is 17050 cd/ m2 at 13 V. Experimental results show that the current density-voltage, luminance-voltage, electroluminescence (EL) spectra and the commission internationale de 1′Eclairage coordinates varying voltage, etc. The current efficiency can improved when select the proper thickness of material acting as excton block-layer, which is the lower cavvier mobility and largely negative HOMO position. The results obtained will be helpful for the optimal design and operation of organic light emitting devices, especially for white organic light emitting device using sub-monolayer emitter.