During the last ten years， near ultraviolet organic light-emitting diodes （NUV-OLEDs） have been widely concerned by researchers due to their NUV photon-emitting capability. However， when the electroluminescence （EL） wavelength is extended below 400 nm， how to increase the radiance of devices has become a technical challenge. In this research， small molecules of BCPO and TAZ with wide bandgap were used as the luminescent material. Then， NUV-OLEDs based on BCPO and TAZ with single unit and tandem structure were fabricated， respectively. And their EL properties were compared. The measurement results show that the EL performance of double unit tandem NUV-OLEDs is significantly better than that of single unit NUV-OLEDs. Single unit BCPO-based NUV-OLEDs showed the maximum external quantum efficiency （EQE_max） of 2.91% and the maximum radiance （R_max） of 34.2 mW/cm². The peak wavelength （λ_EL） was 384 nm and the proportion of NUV light with wavelength below 400 nm （P_NUV） was 56.9% in their EL spectra. In comparison， double unit BCPO-based tandem NUV-OLEDs showed EQE_max = 5.73%， R_max = 52.8 mW/cm²， λ_EL = 384 nm， and P_NUV = 60.5%. Single unit TAZ-based NUV-OLEDs showed EQE_max = 3.65%， R_max = 15.7 mW/cm²， λ_EL = 377 nm， and P_NUV = 79.1%. In comparison， double unit TAZ-based tandem NUV-OLEDs showed EQE_max = 7.21%， R_max = 29.4 mW/cm²， λ_EL = 377 nm， and P_NUV = 79.6%. In addition， tandem NUV-OLEDs exhibited better luminescence stability than that of single unit devices because of the significantly lower current density required for tandem NUV-OLEDs compared to single unit NUV-OLEDs.

organic light-emitting diode;near ultraviolet light;tandem structure;charge generation layer