LGP2 - Study of the ink formulation based on Cu, Zn, Sn S precursors and of the crystallization's annealing for the non-vacuum deposit of photovoltaic layers
Published on April 14, 2015
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March 31, 2015
Thibaut Martini defended his University of Grenoble doctoral thesis entitled "Study of the ink formulation based on Cu, Zn, Sn S precursors and of the crystallization's annealing for the non-vacuum deposit of photovoltaic layers".
Kesterite (CZTS) is a semi-conductor only made of abundant elements. Its direct bangap between 1.0 and 1.5 eV makes it excellent candidate to replace the currently used absorbers in modules photovoltaic in thin coats.
This thesis describes the fabrication of thin films of CZTS by nanoparticles printing followed by crystallization annealing. Different hydrothermal synthesis of nanoparticles have been developed, some in continuous flow reactor, for a development on a larger scale. The influence of the types of precursors and synthesis conditions on the particles chemical composition was studied and their purity was evaluated.
The behavior of the colloidal dispersion is then characterized and three surface functionalizations based on dodecanethiol, dodecyl pyrrolidone and anions sulphides are presented. These stabilizations allow to make an ink-jet and spray ink adapted to the deposit on molybdenum. The printed and dried layers are then annealed in sulfur atmosphere. Annealing of at least 120 minutes is required. However, the growth of the layers is heterogeneous when printed with the nanoparticles stabilized by dodecanethiol and dodecyl pyrrolidone. The presence of carbon in layers, recognizable by spectroscopy Raman, inhibits the growth of the material. Only the thin layers printed by using purified and stabilized by anions sulphides nanoparticles allow the homogeneous growth of the material during annealing.