Aromatic amine-functionalization of silicon nanoparticles induces a new absorption band in the near UV-to-blue region and efficient blue photoluminescence even at room temperature. However, the origin of the absorption band and photoluminescence has not yet been understood well. Here, we study theoretically the electronic structure and light absorption and photoluminescence properties of carbazole-functionalized silicon nanoparticles. We reveal that the absorption band and photoluminescence are attributed to interfacial charge-transfer (ICT) transitions between the covalently-boned carbazole and silicon nanoparticles. The ICT transitions are induced by strong electronic couplings between CA and a silicon nanoparticle via the Si-N bond. (C) 2017 Elsevier B.V. All rights reserved.