Thiol-Free Synthesized Copper Indium Sulfide Nanocrystals as Optoelectronic Quantum Dot Solids

Colloidal semiconductor nanocrystals are a platform for developing applications in optoelectronics but are mostly based on materials with toxic elements. Copper indium sulfide nanocrystals (CIS NCs) are an alternative but have been investigated in only a few reports as a functional optoelectronic film. We synthesized various sizes of emitting copper-poor CIS NCs in the absence of dodecanethiol. We employed a Zn-shelling as a surface stabilizing agent that yielded high quantum yield and stable colloids in both organic and aqueous solvents. We found that these nanocrystals possess high exciton binding energies and exhibit a decrease in photoluminescence lifetimes with distance under the Förster relationship. We then deposited CIS QD films by solid-state ligand exchange and characterized their field effect transistor and photoconductive characteristics.