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 (Ge_1-xE_x 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 Ge_1-xE_x 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 Ge_1-xE_x NCs to be prepared, which exhibit conductivities over large distances (25 μm) relevant to optoelectronic device development of group IV NC thin films.