Surface Chemistry Exchange of Alloyed Germanium Nanocrystals: A Pathway Toward Conductive Group IV Nanocrystal Films

We present an expansion of the mixed-valence iodide reduction method for the synthesis of Ge nanocrystals (NCs) to incorporate low levels (∼1 mol %) of groups III, IV, and V elements to yield main-group element-alloyed Ge NCs (Ge1–xEx NCs). Nearly every main-group element (E) that surrounds Ge on the periodic table (Al, P, Ga, As, In, Sn, and Sb) may be incorporated into Ge1–xEx NCs with remarkably high E incorporation into the product (>45% of E added to the reaction). Importantly, surface chemistry modification via ligand exchange allowed conductive films of Ge1–xEx NCs to be prepared, which exhibit conductivities over large distances (25 μm) relevant to optoelectronic device development of group IV NC thin films.