Amorphous WO3 films via chemical vapor deposition from metallorganic precursors containing phosphorus dopant

Amorphous WO3 films, doped with phosphorus, have been synthesized by chemical vapor deposition of volatile, low-melting P-substituted tungsten carbonyls. The presence of a small quantity of dopant released by the precursor during its decomposition is sufficient to inhibit the crystallization of the tungsten oxide on the matrix (P/W 2-4 atom % on Si(100) and ca. 10 atom % on KGlass). The nature of the film is scarcely affected by the experimental conditions of deposition (namely p(O2) partial pressure) and the quantity of the P dopant is properly tuned by an appropriate choice of the molecular precursor, being in the order W(CO)(4)[P(OEt)(3)](2) (P/W 1/1) > W-2(mu-PR2)(2)(CO)(8) (P/W 1/4) > W(CO)(4)(PEt3)(2) (P/W 1/10 on KGlass, 1/30 on Si). The films on KGlass exhibit interesting electrochromic properties with a maximum efficiency of 66 cm(2)/C.