CuIn(S,Se) 2 thin film solar cells from nanocrystal inks: Effect of nanocrystal precursors

CuIn(S,Se)2 thin film solar cells are fabricated by selenizing CuInS2 nanocrystals synthesized using a variety of copper and indium precursors. Specifically, copper and indium acetates, acetylacetonates, iodides, chlorides and nitrates are investigated to determine the effect of precursors on electronic properties and device performance. Nanocrystal synthesis with each of these precursors can be optimized to yield similar nanocrystal composition, size and structure. In addition, dense chalcopyrite CuIn(S,Se)2 thin films with micron sized grains at the surface are formed upon selenization regardless of precursor type. Surprisingly, solar cells fabricated from each nanocrystal ink have roughly the same carrier concentrations of 1016 to 1017cm−3 in the absorber layer and achieve active area efficiencies of approximately 5%.