title: Colloidally stable selenium@copper selenide core@shell nanoparticles as selenium source for manufacturing of copper-indium-selenide solar cells.
abstract: Selenium nanoparticles with diameters of 100-400nm are prepared via hydrazine-driven reduction of selenious acid. The as-prepared amorphous, red selenium (a-Se) particles were neither a stable phase nor were they colloidally stable. Due to phase transition to crystalline (trigonal), grey selenium (t-Se) at or even below room temperature, the particles merged rapidly and recrystallized as micronsized crystal needles. As a consequence, such Se particles were not suited for layer deposition and as a precursor to manufacture thin-film CIS (copper indium selenide/CuInSe2) solar cells. To overcome this restriction, Se@CuSe core@shell particles are presented here. For these Se@CuSe core@shell nanoparticles, the phase transition a-Se→t-Se is shifted to temperatures higher than 100°C. Moreover, a spherical shape of the particles is retained even after phase transition. Composition and structure of the Se@CuSe core@shell nanostructure are evidenced by electron microscopy (SEM/STEM), DLS, XRD, FT-IR and line-scan EDXS. As a conceptual study, the newly formed Se@CuSe core@shell nanostructures with CuSe acting as a protecting layer to increase the phase-transition temperature and to improve the colloidal stability were used as a selenium precursor for manufacturing of thin-film CIS solar cells and already lead to conversion efficiencies up to 3%.
authors.affiliation: Institut für Anorganische Chemie, Karlsruhe Institute of Technology (KIT), Engesserstraße 15, D-76131 Karlsruhe, Germany.
authors.forename: Hailong
authors.initials: H
authors.lastname: Dong
authors.forename: Aina
authors.initials: A
authors.lastname: Quintilla
authors.forename: Marco
authors.initials: M
authors.lastname: Cemernjak
authors.forename: Radian
authors.initials: R
authors.lastname: Popescu
authors.forename: Dagmar
authors.initials: D
authors.lastname: Gerthsen
authors.forename: Erik
authors.initials: E
authors.lastname: Ahlswede
authors.forename: Claus
authors.initials: C
authors.lastname: Feldmann
mesh_terms: D003102:Colloids; D003300:Copper / Q000737:chemistry*; D011211:Electric Power Supplies; D006834:Hydrazines / Q000737:chemistry; D007204:Indium / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D008855:Microscopy, Electron, Scanning; D010316:Particle Size; D044367:Phase Transition; D020887:Selenious Acid / Q000737:chemistry; D012643:Selenium / Q000737:chemistry*; D012993:Solar Energy; D013499:Surface Properties; D013696:Temperature
chemical_list: D003102:Colloids; D006834:Hydrazines; C101793:copper indium diselenide; D007204:Indium; C029424:hydrazine; D003300:Copper; D020887:Selenious Acid; D012643:Selenium
keywords: CIS; Copper selenide; Core–shell structure; Selenium; Solar cell