In the present work, the enhancement in the efficiency of commercial solar cells through the use of Al₂O₃/ SiNPs multilayer antireflecting coating, is reported. The Al₂O₃ coatings were deposited by the atomic layer deposition technique, while the silicon nanoparticles were synthesized using a water-dispersible methodology. Based on photoluminescence and absorbance studies of the SiNPs, the underlying mechanism for this improvement can be attributed to the luminescent down-shifting effect. Thermoluminescence studies were achieved to confirm the formation of the Al₂O₃ layer. The thickness of the Al₂O₃ thin films were determined by spectroscopic ellipsometry in a range of 25 to 30 nm, while a SiNPs size of approximately 3 nm was obtained using dynamic light scattering method. The coatings of Al₂O₃ with SiNPs nanoparticles were deposited over solar cells to study their efficiency enhancement. Under a simulated one-sun illumination, coated solar cells achieved an enhancement of 6.74 mA/cm², in short-circuit current density; while a 54.9% in power conversion efficiency increase was achieved, relative to those obtained for a pristine cell. The results show that the efficiency of solar cells can be significantly increased by combining the downshifting effect of the Si nanoparticles and the antireflective properties of the Al₂O₃ films.