Design, fabrication and studies on optical properties of new hybrid chitosan films doped with 1, 3, 4-oxadiazole derivatives for down conversion and photoluminescence applications

Abstract The multifunctional chitosan films are fabricated by doping of 5-[4-(benzyloxy)phenyl]-1,3,4-oxadiazol-2-amine (BOPOXD) and 2-([1,1′-biphenyl]-4-yl)-5-[(4-bromophenyl)methyl]-1,3,4-oxadiazole (BPHOXD), by solvent intercalation method. The doping is confirmed by FTIR, SEM and EDS data. The dopant molecules are dispersed as micro and macrocystals in the chitosan matrix. The dopant BOPOXD encapsulated into chitosan matrix by intermolecular H-bonding resulted in red shift (261 nm–340 nm) of λmax. The crystallinity of the doped films increased in dose-dependent manner. The band gap energy lowered to an extent of 1.93eV (4wt %) and 1.84eV (6wt %) for BOPOXD and BPHOXD respectively which is comparable with known semiconductors like TiO2 and CdSe etc. The change observed in calculated refractive index, dielectric constant, optical conductivity from UV data evidenced interaction of the dopants with the matrix. The non-luminescent films turned out to be excellent photoluminescent materials on doping; with maximum intensity at 4wt% dopant concentration for both the dopants. The predicted absolute quantum yield for the chitosan BOPOXD films obtained in a range of 16.28%–31.48% and for the chitosan- BPHOXD films in the range of 24.35%–38.61%.