An Al2O3 antireflection layer was placed between a glass substrate and a transparent conducting oxide layer in order to decrease optical reflection in microcrystalline silicon (mu c-Si:H) p-i-n solar cells. Optical simulations showed that reflections were decreased by Al2O3 thin films, these reflections were found to be at a minimum when a 40 nm thick Al2O3 layer was used. Experimental results demonstrated that the measured reflectance of mu c-Si:H solar cells was decreased by employing the proposed 40 nm Al2O3 in all wavelength regions and the quantum efficiency was also increased. The short-circuit current was increased from 22.7 to 23.5 mA/cm(2) without sacrificing open circuit voltage or fill factor. The average efficiency of devices was improved from 6.02% to 6.32% by introducing 40 nm Al2O3 antireflection layer. (C) 2012 Elsevier B.V. All rights reserved.