Synthesis of Alq3 by a facile co-precipitation approach and study the impact of CNTs support on its microstructure and electronic characteristics for photodiode development

Abstract

The global demand for renewable energy as an alternative to traditional fossil fuels has motivated the scientific community to develop highly efficient nanocomposite materials that can be used for enhancement to optoelectronic technology. In the present work, organometallics Alq _3 and Alq _3 /CNTs were prepared by cost-effective chemical route. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were performed to identify the structural and morphological features. The hybrid Alq _3 /CNTs exhibited polycrystalline structure with a large surface area. The optical band gap $({{\rm{E}}}_{{\rm{g}}})$ of Alq _3 film was evaluated within the visible spectrum in the range of 3.047 eV which reduced to 2.979 eV by CNTs integration. Ag/Alq _3 /p-Si/Al and Ag/Alq _3 /CNTs/p-Si/Al photodiodes were fabricated using thermal evaporating technique. Current-voltage $({\rm{I}}-{\rm{V}})$ and capacitance/conductance-voltage $({\rm{C}}/{\rm{G}}-{\rm{V}})$ were measured to analyze the photodiode behavior. The main electronic parameters like ${{\rm{R}}}_{{\rm{s}}},\,{\rm{n}},\,{\phi }_{{\rm{b}}}{\,{\rm{and}}\,{\rm{I}}}_{{\rm{o}}}$ were determined using different models indicating that the composite photodiode of high performance in which ${{\rm{R}}}_{{\rm{s}}}$ was decreased whereas ${{\rm{N}}}_{{\rm{a}}}$ was increased with doping. Besides, the photocurrent sensitivity was increased from $1.45\times {10}^{-8}\,{\rm{A}}\,$ to $1.1\times {10}^{-5}\,{\rm{A}}$ due to increase of free charge carriers.

Keywords

• organometallic Alq3
• Alq3/CNTs nanocomposite
• energy gap
• electronic parameters
• hybrid photodiode