Study of Photoluminescence Properties of ZnO Nanoparticles Synthesised from Plant Extracts in Abeokuta, Ogun State

Background: Zinc oxide nanoparticles synthesised via green methods using plant extracts have attracted interest for optoelectronic and sensing applications due to their tunable photoluminescence and low synthesis cost. Aim: This study investigated the photoluminescence properties of ZnO nanoparticles synthesised using pawpaw leaf extract from Abeokuta, Ogun State, South West Nigeria. Methods: ZnO nanoparticles were synthesised by reacting zinc nitrate hexahydrate with pawpaw leaf extract at 60 degrees Celsius for 2 hours, followed by calcination at 400 degrees Celsius. Particle size and morphology were characterised using X-ray diffraction and transmission electron microscopy. Photoluminescence spectra were measured using a spectrofluorometer with 325 nm excitation. Results: X-ray diffraction confirmed a hexagonal wurtzite crystal structure with mean crystallite size of 22 nm. Photoluminescence spectra showed a strong UV emission at 380 nm and a broad visible emission centred at 520 nm attributed to oxygen vacancies. Emission intensity increased with decreasing particle size. Conclusion: Pawpaw extract-synthesised ZnO nanoparticles exhibit promising photoluminescence for UV sensor and light-emitting device applications. Green synthesis using locally available plant extracts offers a sustainable and cost-effective fabrication route. Keywords: ZnO nanoparticles, photoluminescence, green synthesis, Abeokuta, optoelectronics.