title: Phase conversion from hexagonal CuS(y)Se(1-y) to cubic Cu(2-x)S(y)Se(1-y): composition variation, morphology evolution, optical tuning, and solar cell applications.
abstract: In this work, we report a simple and low-temperature approach for the controllable synthesis of ternary Cu-S-Se alloys featuring tunable crystal structures, compositions, morphologies, and optical properties. Hexagonal CuS(y)Se(1-y) nanoplates and face centered cubic (fcc) Cu(2-x)S(y)Se(1-y) single-crystal-like stacked nanoplate assemblies are synthesized, and their phase conversion mechanism is well investigated. It is found that both copper content and chalcogen composition (S/Se atomic ratio) of the Cu-S-Se alloys are tunable during the phase conversion process. Formation of the unique single-crystal-like stacked nanoplate assemblies is resulted from oriented stacking coupled with the Ostwald ripening effect. Remarkably, optical tuning for continuous red shifts of both the band-gap absorption and the near-infrared localized surface plasmon resonance are achieved. Furthermore, the novel Cu-S-Se alloys are utilized for the first time as highly efficient counter electrodes (CEs) in quantum dot sensitized solar cells (QDSSCs), showing outstanding electrocatalytic activity for polysulfide electrolyte regeneration and yielding a 135% enhancement in power conversion efficiency (PCE) as compared to the noble metal Pt counter electrode.
authors.affiliation: School of Electronic Science and Applied Physics, Hefei University of Technology , Hefei, 230009, People's Republic of China.
authors.forename: Jun
authors.initials: J
authors.lastname: Xu
authors.forename: Xia
authors.initials: X
authors.lastname: Yang
authors.forename: Qingdan
authors.initials: Q
authors.lastname: Yang
authors.forename: Wenjun
authors.initials: W
authors.lastname: Zhang
authors.forename: Chun-Sing
authors.initials: CS
authors.lastname: Lee
keywords: Cu2−xSySe1−y; CuSySe1−y; composition tuning; counter electrodes; optical properties