A study of the effect of hydrogen annealing on antireflection and surface passivation properties of sol-gel derived aluminum rich zinc oxide (AZO) films coated on silicon wafers has been done in 300-600 degrees C temperature range. The minority carrier lifetime in silicon wafers coated with AZO films was measured using microwave photoconductive decay (mu-PCD) technique. After annealing of AZO coated silicon wafer in hydrogen ambient for 30 min between 400 and 600 degrees C the effective minority carrier lifetime tau(eff) improved above the initial value of similar to 16 mu s and attained a maximal value of similar to 71 mu s for annealing at 500 degrees C. It may be that above 400 degrees C the molecular hydrogen gets dissociated into atomic hydrogen in presence of Al induced defects at the AZO coated silicon surface and passivates them by formation of Si-H-Al complex. The annealing in air in the same temperature range did not affect the lifetime. AZO films annealed at 500 degrees C in hydrogen or air show high transmittance in 400-1200 nm wavelength range and are suitable as AR coatings for silicon solar cells. We have applied a hydrogen annealed AZO antireflection coating on n(+) front surface and an equally thick hydrogen annealed AZO coating on the p-back surface of an n(+)-p multi crystalline silicon solar cell. The observed improvement in J(sc), V-oc values of the cell established that while AZO film on front acted as a good AR coating the AZO film on the back surface passivated the back surface effectively. (C) 2011 Elsevier B.V. All rights reserved.