The critical role that dopants play in semiconductor devices has stimulated research on the properties and the potential applications of semiconductor nanocrystals. Hence the investigation of the role of dopant concentration on the properties of semiconductor nanoparticles is very important from the viewpoints of basic physics as well as applications. In this context, in the present work Al-doped ZnO (AZO) nanoparticles were synthesized by simple wet chemical route. The structure and morphology of the nanoparticles analyzed using X-ray diffraction (XRD) and scanning electron microscopy (SEM) revealed hexagonal wurtzite structure with flower-like clusters consisting of multi-nanorods. Energy Dispersive Spectrum (EDS) confirms the substitution of Al into ZnO lattice. Defect analysis and excitonic effect of the nanoparticles were investigated by photoluminescence (PL) and UV-Vis absorption measurements, respectively. Optical absorption showed band gap broadening due to quantum confinement effect. PL measurements exhibited both near band edge (NBE) and deep level (DL) emissions. The effect of doping concentration on the growth, crystallization and defect distribution of AZO nanoparticles was studied.