CuGaS₂–CuInE₂ (E = S, Se) Colloidal Nanorod Heterostructures

Colloidal nanorod heterostructures of I–III–VI2 semiconductors have been synthesized in a solution starting from wurtzite-like CuGaS2 nanorods. Growth of CuInS2 or CuInSe2 on CuGaS2 nanorods results in interesting sawtooth structures with larger lattice strain leading to sharper, more pronounced teeth. A final inorganic shell of ZnSe or ZnS grown on the CuGaS2/CuInSe2 nanorod heterostructures enhances photoluminescence. Unusual brush-like structures arise with prolonged ZnSe growth. Time-resolved photoluminescence measurements on CuGaS2/CuInSe2/ZnS nanorod heterostructures reveal a lifetime approaching one microsecond, suggesting charge separation within the nanorods. The results shown here provide previously unknown nanorod heterostructures exhibiting interesting and potentially useful optical properties along with insights into heterostructure formation in colloidal I–III–VI2 nanorods.