Organic Light-Emitting Diodes Based on Deep-Blue Exciplex for Plant Growth

In order to obtain organic light-emitting diodes OLEDs that can be used in plant lighting and have red and blue spectra, two typical carrier transport materials are used, N,N'-bis(1-naphthyl)-N,N'- Diphenyl-(1,1'-biphenyl)-4,4'-diamine (NPB) and 1,3,5-tris(1-phenyl-1 H-benzo[d]imidazole-2- TPBi forms a deep blue exciplex by interface contact or doping, and combines it with the red phosphorescent material Ir(DMP-IQ)2(acac), and the spectrum of the prepared OLED device meets the requirements of plant photosynthesis. By changing the thickness of the spacer layer between the deep blue exciplex complex and the red light emitting layer in the device structure, the blue/red light intensity ratio in the electroluminesence spectrum can be adjusted. On the basis of the structure of exciplex formed by doping, the host material (mCP) is incorporated into the NPB:TPBi film to form a ternary system, which reduces the quenching of exciton caused by carrier accumulation in the film. Under the experimental conditions of a doping ratio of NPB:TPBi:mCP of 1:1:3, a turn-on voltage of 2.8 V, a brightness of 4528 cd/m(2), a current efficiency of 3.09 cd/A and an external quantum efficiency of 6.96% are obtained.