Adjusting White OLEDs with Yellow Light Emission Phosphor Dye and Ultrathin NPB Layer Structure

Figure 5

Normalized EL spectra of four organic devices at 12 V bias (normalized with the emission peak at 560 nm, device A: 3 wt% doping and mixed CPB : NPB thin layer; device B: 3 wt% doping and pure NPB thin layer; device C: 5 wt% doping and mixed CPB : NPB thin layer; device D: 5 wt% doping and pure NPB thin layer). The inset was the AFM testing result of 30 nm NPB film on glass substrate.