Synthesis of Iron Chalcogenide Nanocrystals and Deposition of Thin Films from Single Source Precursors

Abstract

Recently there is growing interest for the production of cheap and nontoxic colloidal nanomaterials or thin films for photovoltaic applications. Iron chalcogenides are cheapest materials available for solar cell applications. The work presented here involve the synthesis of iron chalcogenide nanocrystals by colloidal methods and the deposition of thin films by aerosol assisted chemical vapour deposition (AACVD) method from single source precursors. In addition, a comprehensive literature review of iron chlacogenide nanocrystals and thin films is presented.Several new iron complexes belonging to thiocarbamato, xanthato, selenoureato and imidodiphosphinato, have been synthesised. Tris(dialkyldithiocarbamato)-iron(III) complexes of general formula [Fe(S2CNRR')3] where R = Et, R' = iPr; R, R' = Hex; R = Me, R' = Et and R, R' = Et and tris(O-alkylxanthato)iron(III) complexes of general formula [Fe(S2COR)3] where R = Me, Et, ipr and iBu have been synthesised. The X-ray single crystal structure of [Fe(S2CNEtiPr)3], Fe(S2CNEtMe)3 and [iPrOC(S)S-S(S)COiPr] were determined. Iron complexes were used as a single source precursors for the deposition of iron sulfide nanocrystals by thermolysis in oleylamine, hexadecylamine and octadecene and thin films on silicon substrate at different temperatures. The complexes show typical paramagnetic behaviours whereas the iron sulfide nanocrystals produced show ferromagnetic behaviour. The greigite and pyrrhotite phases with hexagonal and cubic morphology were obtained by thermolysis. Pyrite and pyrrhotite phases were dominant in thin films. The complex tris(N,N-diethyl-N'-naphthoylselenoureato)iron(III) and its X-ray single crystal structure is also reported. Long rod like nanocrystals of orthorhombic ferroselite (FeSe2) obtained by thermolysis in oleylamine, dodecanthiol and in the mixture of oleylamine and dodecanthiol at 190, 240, and 290 °C. Paramagnetic behaviour was found under magnetic measurement of iron selenide nanocrystals. A very thin film of iron selenide (FeSe) phase was deposited on silicon substrate at 625 °C by AACVD method. The complexes [Fe{(SePiPr2)2N}2] and [Fe{(SePPh2)2N}2] were synthesised. The X-ray single crystal structure of [Fe{(SePPh2)2N}2] and [(SePPh2)2N)-O-(SePPh2)2N)] were also reported. A mixture of orthorhombic ferroselite (FeSe2) with rod and plate-like crystallites was obtained from the thermolysis of these complexes in oleylamine and hexadecylamine at 190, 240 and 290 °C temperatures. Also the mixed phases of iron selenide (Fe7Se8 and FeSe2) thin films having rod and sheet-like morphology were deposited at different deposition temperature (500, 550 and 600 °C) onto silicon substrates from these complexes.

Date of Award	31 Dec 2013
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Paul O'Brien (Supervisor)