Novel Heteroleptic Tin(II) Complexes Capable of Forming SnO and SnO Thin Films Depending on Conditions Using Chemical Solution Deposition.

A new heteroleptic complex series of tin was synthesized by the salt metathesis reaction of SnX (X = Cl, Br, and I) with aminoalkoxide and various -alkoxy-functionalized carboxamide ligands. The complexes, [ClSn(dmamp)] (), [BrSn(dmamp)] (), and [ISn(dmamp)] (), were prepared from the salt metathesis reaction of SnX with one equivalent of dmamp; [Sn(dmamp)(empa)] (), [Sn(dmamp)(mdpa)] (), and [Sn(dmamp)(edpa)] () were prepared via the salt metathesis reaction using complex with one equivalent of -alkoxy-functionalized carboxamide ligand. Complexes - displayed dimeric molecular structures with tin metal centers interconnected by μ-O bonding via the alkoxy oxygen atom. The molecular structures of complexes - showed distorted trigonal bipyramidal geometries with lone pair electrons in the equatorial position. Using complex as a tin precursor, SnO films were deposited by chemical solution deposition (CSD) and subsequent post-deposition annealing (PDA) at high temperatures. SnO and SnO films were selectively obtained under controlled PDA atmospheres of argon and oxygen, respectively. The SnO films featured a tetragonal romarchite structure with high crystallinity and a preferred growth orientation along the (101) plane. They also exhibited a lower transmittance of >52% at 400 nm due to an optical band gap of 2.9 eV. In contrast, the SnO films exhibited a tetragonal cassiterite crystal structure and an extremely high transmittance of >97% at 400 nm was observed with an optical band gap of 3.6 eV.