AbstractWurtzite‐phase Cu2SnSe3 colloidal nanocrystals are synthesized by fast addition of tBu2Se2 to a solution of CuCl and SnI4 in dodecylamine and 1‐dodecanethiol at 180 °C, followed by heating for 5 min.

A new wurtzite phase of copper tin selenide (CTSe) was discovered, and the resulting nanocrystals were synthesized via a facile solution-phase method. The wurtzite CTSe nanocrystals were synthesized with dodecylamine and 1-dodecanethiol as coordinating solvents and di-tert-butyl diselenide ((t)Bu(2)Se(2)) as the selenium source. Specific reaction control (i.e., a combination of 1-dodecanethiol with (t)Bu(2)Se(2)) was proven to be critical in order to obtain this new phase of CTSe, which was verified by powder X-ray diffraction and selected area electron diffraction. The wurtzite CTSe nanocrystals possess an optical and electrochemical band gap of 1.7 eV and display an electrochemical photoresponse indicative of a p-type semiconductor.

Nanocrystals of CuInSe2 with a metastable wurtzite crystal structure were synthesized for the first time. The keys to wurtzite−CuInSe2 formation include the use of an amine solvent and facile selenium transfer from a diorgano diselenide at relatively low temperatures.

Well-defined and monodisperse wurtzite Cu−In−S nanocrystals were synthesized via a solution-based method using di-tert-butyl disulfide as the sulfur source. Reaction control (i.e., coordinating solvent, capping ligand, and sulfur source) proved critical for providing a kinetic pathway to the metastable wurtzite phase. The crystal phase was confirmed by powder X-ray diffraction and selected area electron diffraction. Quantitative nanocrystal growth kinetics were studied on a Cu−In−S system for the first time, clearly showing that the nanocrystals pass through a size focusing event before undergoing steady-state Ostwald ripening at later stages of growth. The size-focused 6.9 nm Cu−In−S nanocrystals have an optical band gap of Eg = 1.47 eV and an electrochemical band gap of Eg = 1.84 eV.