Study the Effect of the Volumetric Ratio of Alq3 on the Optical and Structural Properties of the Alq3:NPD Blend for the UV Photodetector Applications

Abstract

The effect of the volumetric ratio of the tris(8-hydroxyquinoline) aluminum (Alq3) on its blend with the N,N'-Di [(1-naphthyl)-N,N'-diphenyl]-(1,1'-biphenyl)-4,4'-diamine (NPD) (Alq3:NPD) is investigated and optimized for the UV photodetectors fabrication. The optical and structural properties of Alq3:NPD blend with different volumetric ratios 1:1, 2:1, and 3:1 is studied in the context of the absorbance, transmittance, optical energy gap and XRD patterns. Results show that the absorbance is increased by 11% at A = 260 nm with the increase in the volumetric ratio. In contrast, the optical energy bandgap that is extrapolated from the Tauc’s plot is decreased with the increase in the volumetric ratio, and the 2:1 ratio shows the lowest energy in the UV region. In terms of the XRD investigation, the 2:1 volumetric ratio shows the highest intensity for the crystallinity peak at 36.6°. The fabricated photodetector with a different volumetric ratio of the active layer Alq3:NPD blend shows the best performance with the ratio 2:1.