Quaternary n-type Al0.08In0.08Ga0.84N grown on p-Si using molecular beam epitaxy technique was fabricated as a pn-junction and an anti-reflection coating (ARC) of solar cells. The structural properties and surface morphology of the solar cells were investigated using scanning electron and atomic force microscopy. Optical reflectance was obtained using an optical reflectometery system (Filmetric F20-VIS). Current–voltage characteristics were examined under 100mWcm−2 illumination conditions. Quaternary n-type Al0.08In0.08Ga0.84N coating was found to be an excellent ARC against incident light compared with other ARCs. This material also exhibited good light trapping over a wide wavelength spectrum, which produced highly efficient solar cells. The unique and strong polarization, as well as the piezoelectric effect, of the quaternary-nitrides was employed to reduce surface recombination velocities and enhance the solar cell performance. A solar cell with reasonable conversion efficiency of 9.74% was obtained when the n-Al0.08In0.08Ga0.84N/p-Si was employed.