Structural, optical and photoconductivity characteristics of pristine FeO·Fe2O3 and NTPI–FeO·Fe2O3 nanocomposite: aggregation induced emission enhancement of fluorescent organic nanoprobe of thiophene appended phenanthrimidazole derivative

Abstract

In this manuscript we report the successful synthesis of pristine FeO·Fe₂O₃, 1-(naphthalen-1-yl)-2-(thiophen-2-yl)-1H-phenanthro[9,10-d]imidazole (NTPI), fluorescent organic nanoparticles (FONs) of NTPI and NTPI–FeO·Fe₂O₃ nanocomposite. Pristine FeO·Fe₂O₃ and NTPI–FeO·Fe₂O₃ nanocomposite were characterised by XRD, SEM, EDS, TEM, SAED, XPS, DLS, UV, PL, life time FT-IR and magnetic hysteresis. We have extensively studied the photoluminescence and photoconductivity of both pristine FeO·Fe₂O₃ and NTPI–FeO·Fe₂O₃ nanocomposite. An enhancement in photoluminescence (PL) emission and reduced photoconductivity is observed for NTPI–FeO·Fe₂O₃ nanocomposite when compared to bare FeO·Fe₂O₃. NTPI adsorption on FeO·Fe₂O₃ reduces the non-radiative trap levels at the interface, resulting enhancement of PL intensity of nanocomposite. For FeO·Fe₂O₃, exponential rise and decay in photocurrent is observed upon UV irradiation in the ON and OFF state, respectively and unusual behavior of photocurrent is observed for NTPI–FeO·Fe₂O₃ composite. The NTPI behave as AIEE-active chemosensor for the detection of ferric ions in aqueous solution. Theoretical investigation shows that the binding energy and energy gap of the imidazole composites are highly dependent on the nature of the iron oxide cluster and the existence of charge transfer in the imidazole–iron oxide composite is explained.