We report the effects of introducing an undoped Si1-xCx buffer layer between a silicon nanocrystal (nc-Si) active layer and an n-type SiC layer on the performance of the nc-Si light-emitting diodes (LEDs). The electrical property of an nc-Si LED with a buffer layer was greatly improved compared to that of an nc-Si LED without a buffer layer. Moreover, the light output power of the nc-Si LED with a buffer layer was enhanced by a factor of 2. By employing a buffer layer, the efficiency of electron injection into the nc-Si layer was enhanced, which resulted in an increase in the light output power. The data show that the introduction of an undoped Si1-xCx buffer layer is a very effective way to improve the performance of nc-Si LEDs. (C) 2008 The Electrochemical Society.