Cu 3-x P nanocrystals were synthesized according to previously reported methods. Thermal decomposition of copper-triphenylphosphite complex in oleylamine/hexadecylamine produced these nanocrystals. The resulting nanocrystals had a broad plasmon resonance in the NIR region between 1000 nm and 2000 nm as shown in Figure . The absorption spectrum in the visible region had no distinct features. TEM images showed that these nanocrystals were monodispersed and had an average size of 5.4 nm (Figure ). Powder x-ray diffraction (PXRD) patterns of the synthesized samples matched with characteristic peaks of bulk Cu 3-x P as shown in Figure .