Three-dimensional self-assembly of chalcopyrite copper indium diselenide nanocrystals into oriented films.

Reifsnyder, Danielle C; Ye, Xingchen; Gordon, Thomas R; Song, Chengyu; Murray, Christopher B · ACS Nano · 2013

basic_science · Level V

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Abstract

CuInSe2, which is one of the highest efficiency thin-film solar cell active layer materials, has been an attractive target for nanocrystal synthesis and manipulation. Here, we report unprecedented, simultaneous control of the synthesis and self-assembly behavior of CuInSe2 nanocrystals. These nanocrystals are solution-processable, monodisperse tetragonal bipyramids that exhibit photoconductivity and self-assemble into crystallographically oriented thin films. Structural characterization indicates that these nanocrystals are tetragonal phase, as is used in high-efficiency, second-generation, thin-film solar cells. Elemental analysis indicates that approximately 1:1:2 Cu/In/Se stoichiometry can be achieved, and that the elemental composition can be adjusted from copper-rich to indium-rich with reaction time.