Optimizing efficiency of polycrystalline p-Si anode organic light-emitting diode

Optimizing efficiencies of organic light-emitting diodes (OLEDs) with a structure of Al/glass/nanometer-thick polycrystalline p-Si (NPPS) anode/SiO₂/N′-bis-(1-naphthl)-diphenyl-1,1′-biphenyl-4,4′-diamine (NPB)/tris (8-hydroxyquinoline) aluminum (Alq₃)/4,7-diphenyl-1,10-phenanthroline (BPhen):Cs₂CO₃/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 efficiency of the OLED was optimized. When the resistivity of the p-Si target is 0.01 Ω·cm, the current and power efficiencies 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.