Library of semiconductors: Mixtures of binary chalcogenidostannate anions in protic solution show statistic chalcogenide exchange (see scheme), which is examined by comprehensive NMR investigations, DFT calculations and chemical reactions. A simple approach is provided to generate a library of semiconductor compounds with finely tuned opto-electronic properties.
Aqueous solutions of ternary ortho-chalcogenidostannate anions [SnE14−xE2x]4− (E1, E2=S, Se, Te) have been generated following different routes that all lead to equilibria of all possible permutations of binary and ternary anions. This has been rationalized by means of NMR studies that can be explained by calculations using density functional theory (DFT) methods. Thus, if one reacts such solutions with transition-metal ions, quaternary M/Sn/E1/E2 anions are obtained, which exhibit coordination by different ternary chalcogenidostannate ligands. The electronic excitation energies of the corresponding alkali metal salts lie between the Eg values of compounds containing either M/Sn/E1 or M/Sn/E2 anions. In this way, we provide a simple approach toward a library of semiconductor compounds with finely-tuned optoelectronic properties.