Direct Chemical Vapor Deposition Synthesis of Phase-Pure Iron Pyrite Thin Films

摘要

Iron pyrite has seen a renewed interest in the past few years as a promising earth-abundant, non-toxic semiconductor material for solar energy conversion. Pyrite has many appealing properties such as direct/indirect bandgaps of 1.03 & 0.95 eV, large absorptivity of 6×105 cm-1,[1] and high carrier mobility (for single crystals).[2,3] However, recent attempts to make solar cells using pyrite nanostructures or thin films have been hampered by the presence of impurity phases (such as the marcasite polymorph)[4] and an observed defect-induced degenerately-doped behavior,[5-8] which lead to low or no photovoltage.[1,9] Even though we have shown methods to synthesize phase-pure pyrite nanowires, nanorods, nanobelts and nanoplates.[10,11] To date, the only means of synthesizing phase purity pyrite thin films requires a harsh sulfidation step at high temperatures to eliminate the other impurity phases.[4]