Direct Synthesis of Highly Conductive tert ‐Butylthiol‐Capped CuInS 2 Nanocrystals

tert ‐butylthiol ( t BuSH) is used as the sulfur source, surface ligand and co‐solvent in the synthesis of CuInS 2 nanocrystals (NCs). The presented method gives direct access to short‐ligand‐capped NCs without post‐synthetic ligand exchange. The obtained 5 nm CuInS 2 NCs crystallize in the cubic sphalerite phase with space group F‐43m and a lattice parameter a =5.65 Å. Their comparably large optical and electrochemical band gap of 2.6–2.7 eV is attributed to iodine incorporation into the crystal structure as reflected by the composition Cu 1.04 In 0.96 S 1.84 I 0.62 determined by EDX. Conductivity measurements on thin films of the t BuSH‐capped NCs result in a value of 2.5 . 10 −2  S m −1 , which represents an increase by a factor of 400 compared to established dodecanethiol‐capped CuInS 2 NCs.