Tin(IV) Methylselenolate as a Low Temperature SnSe Precursor and Conductive “Glue” Between Colloidal Nanocrystals

We report the synthesis of a soluble precursor that transforms into crystalline SnSe at 200 °C. This transformation temperature is significantly lower than the 270–350 °C range of previously reported tin selenide precursors. This precursor is synthesized by reacting tin with dimethyl diselenide and we identify the precursor as tin(IV) methylselenolate using a combination of mass spectrometry, Raman spectroscopy, and nuclear magnetic resonance spectroscopy. We then chemically treat PbSe colloidal nanocrystals with this precursor and subject them to mild annealing. We characterize the chemical and structural changes during this processing using infrared spectroscopy, aberration-corrected scanning transmission electron microscopy, and X-ray photoelectron spectroscopy. These characterization studies indicate the successful formation of a SnSe-like material that fills the interstitial space between the PbSe nanocrystal cores. We find that the electrical conductivity of these nanocrystal films is comparable to other excellent treatments used to improve charge transport. This excellent charge transport demonstrates the utility of tin(IV) methylselenolate as a conductive “glue” between nanocrystals.