In the present work, we studied the photon down-conversion effect produced by thin films of silicon oxide with embedded silicon nanocrystals also called silicon-rich oxide (SRO). These films have been used to absorb high energy light and the re-emission of two or more low energy photons (similar to 1.1eV) with the goal of improving the external quantum efficiency and consequently the conversion efficiency of silicon solar cells. According to our results, the incorporation of a thin SRO film on the solar cell surface increases the short circuit current and the FF of the silicon solar cells; the enhancement of spectral response is due to the high photoluminescence intensity of the SRO in the visible region when irradiated with UV light. An improvement of 38% in the solar cell efficiency has been observed in our particular solar cell fabrication process by the use of an SRO film with high photoluminescence intensity, which replaces the conventional silicon dioxide film. Copyright (C) 2016 John Wiley & Sons, Ltd.