[Cu₄{Se₂P(O<i>ⁱ</i>Pr)₂}₄]:  A Novel Precursor Enabling Preparation of Nonstoichiometric Copper Selenide (Cu₂_-<i>_x</i>Se) Nanowires

Abstract

A newly synthesized, selenium-bridged copper cluster [Cu 4 {Se 2 P(O i Pr) 2 } 4 ] was employed in a single-source chemical vapor deposition (SSCVD) process to produce single-crystalline nonstoichiometric Cu 2 - x Se nanowires for the first time. This is the first discrete, chalcogen-bridged copper cluster being used successfully for the fabrication of 1D copper chalcogenide nanostructure. The crystalline structure and chemical composition of the resulting nanowires were examined and confirmed with X-ray diffraction, high-resolution transmission electron microscopy, and energy-dispersive X-ray spectrometry analyses. Relevant characterizations revealed that a thin film of CuSe was first formed on the substrate surface due to the thermal decomposition of [Cu 4 {Se 2 P(O i Pr) 2 } 4 ]; subsequently, the Cu 2 - x Se nanowires were grown on the CuSe thin film through a self-catalytic vapor−liquid−solid (VLS) growth mechanism with the Cu particles generated in-situ acting as the catalyst. The Cu 2 - x Se nanowires were found to possess a direct band gap absorption at 558 nm and emit excitonic photoluminescence at 575 nm.