Highly efficient dye-sensitized solar cells (DSSCs) by effective electron injection with GaN nanoparticles are developed. The J-V characteristics of the DSSCs with the nanostructure GaN layer showed 37.6% improvement in the photovoltaic energy conversion efficiency because the potential difference derived from the difference between the CBs of TiO(2) and GaN could transfer electrons effectively and prevent back electron transfer to the dye and electrolyte resulting in a low reverse current. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3583505] All rights reserved.