Hydrothermally synthesized polyaniline/copper oxide nanocomposites: a study on structural, optical, and photoluminescence properties

Abstract

The hydrothermal method was employed for the synthesis of polyaniline conductive polymer, and its combination with copper oxide semiconductor. Infrared spectral analysis confirmed the formation of both pristine and copper oxide-doped polyaniline. The material exhibited a well-defined heterogeneous structure comprising polyaniline nanoflakes and copper oxide nanoparticles with particle sizes ranging from 31 to 36 nm, as confirmed by scanning electron micrographs and energy dispersive X-ray analysis. Powder X-ray diffraction analysis confirmed the semicrystalline nature of pristine polyaniline and the co-existence of crystalline peaks for both divalent (CuO) and monovalent (Cu₂O) copper oxide. Interestingly, optical absorption and band gap calculations revealed a consistent optical band gap for both pristine and copper oxide-doped polyaniline. Photoluminescence analysis showed significant changes in the electronic structure upon doping and interaction between polyaniline and copper oxide. Notably, the pure PANI sample possesses a strong and sharp emission peak in the visible light region. Furthermore, the incorporation of copper oxide effectively quenched the photoluminescence emission of pure sample. The variation in the emission peak position is attributable to the electron–hole recombination mechanisms. PL quenching is concentration-dependent, indicating that the amount of CuO directly influences quenching efficiency. Energy transfer and/or electron transfer are the most likely mechanisms responsible for this quenching, with each mechanism playing a role depending upon the specific conditions of the PANI/CuO interaction. This dual mechanism highlights the complex nature of energy transfer in these nanocomposites. Our results suggest that the hydrothermally synthesized polyaniline/copper oxide nanocomposites are promising candidates for PL, OLEDs, and OPVs applications.