Optimizing ef?ciencies of organic light-emitting diodes(OLEDs) with a structure of Al/glass/nanometerthick polycrystalline p-Si(NPPS) anode/SiO_2/N'-bis-(1-naphthl)-diphenyl-1,1'-biphenyl-4,4'-diamine(NPB)/tris(8-hydroxyquinoline) aluminum(Alq_3)/4,7-diphenyl^(-1),10-phenanthroline(BPhen):Cs_2CO_3/Sm/Au were studied. The NPPS anodes were fabricated by magnetron sputtering(MS)Si and Ni layers followed by Ni-induced crystallization of the amorphous Si layers. By adjusting the resistivity of the p-Si target adopted in MS, the electroluminescent ef?ciency of the OLED was optimized. When the resistivity of the p-Si target is 0.01 Ω·cm, the current and power ef?ciencies of the NPPS anode OLED reach maximum values of 6.7 cd ·A^(-1)and 4.64 lm ·W^(-1), respectively, which are 2.7 and 3.1 times those of the resistivity-optimized bulk p-Si anode counterpart and 2.9 and 3.7 times those of the indium tin oxide(ITO) anode counterpart, and then, the physical reasons were discussed.
Electroluminescence peaking at 1.3 μm is observed from high concentration boron-diffused silicon p^+-njunctions.This emission is efficient at low temperature with a quantum efficiency 40 times higher thanthat of the band-to-band emission around 1.1 μm,but disappears at room temperature.The 1.3-μm bandpossibly originates from the dislocation networks lying near the junction region,which are introduced byhigh concentration boron diffusion.
