Synthesis, characterization and optical-electrical properties of nano Al(III)-8-hydroxy-5,7-dinitroquinolate thin films

• Layer-by-layer complexation of Al(III)-8-hydroxy-5,7-dinitroquinolate (8HQ) films.
• Al((NO2)2-8HQ)3] thin film with particle size of 16-33 nm.
• [Al((NO2)2-8HQ)3] film showed direct transition with band gap of 2.42 eV.
• Dark current-voltage characteristics of [Al((NO2)2-8HQ)3]/p-Si showed rectification effect.

Layer-by-Layer self-assembly technique was used to synthesize nano [Al((NO2)2-8HQ)3] thin films from aluminum nitrate, Al(NO3)3·9H2O and 8-hydroxy-5,7-dinitroquinoline [(NO2)2-8HQ] solutions. Stoichiometry and structure were confirmed by elemental analysis and Fourier transform infrared spectra. Scanning electron microscopy showed a particle size in the range of 16-33 nm. Thermogravimetric analysis was used to determine the thermal stability of the synthesized nano complex.The UV–vis absorption spectrum for [Al((NO2)2-8HQ)3] film showed a peak at 358 nm and a shoulder around 433 nm, mainly due to the electronic π → π* transition from the highest occupied molecular orbital to the lowest unoccupied molecular orbital. Analysis of the spectral behavior revealed a direct allowed transition with band gap of 2.42 eV. The electrical parameters of [Al((NO2)2-8HQ)3]/p-Si device were investigated using forward and reverse bias current–voltage (I–V) and capacitance–voltage measurements in dark at room temperature. Dark I–V characteristics showed a rectification effect due to junction barrier of [Al((NO2)2-8HQ)3]/p-Si heterojunction.