Xuerong Zheng

Chemical synthesis of MSe2 (M = Ni, Fe) particles by triethylene glycol solution process

Pyrite star-shaped nickel diselenide and marcasite laminar iron diselenide particles were prepared by a solution chemical process using triethylene glycol as solvent. The influence of synthetic temperatures was investigated and the products were characterized by XRD, FESEM, TEM (SAED), Raman, UV–vis-NIR measurements.

Morphological growth and phase formation of CuInSe2 nanocrystals by an ambient pressure polylol-based solution synthesis

Single-phase and well-dispersed CuInSe2 nanoparticles and nanoplates were successfully synthesized through an ambient pressure solution chemical process using green triethylene glycol (TEG) as solvent, copper(II) chloride, indium(III) chloride and selenium powder as precursor sources. Morphological growth of the CuInSe2 nanoparticles and nanoplates synthesized respectively with the hydrazine- and ethylenediamine-assisted TEG reaction solution was investigated by XRD, TEM, HRTEM, SAED, XPS and EDX analysis. The results showed that the growth process of CuInSe2 nanoparticles derived from the hydrazine-assisted solution only underwent quick reduction reaction of elemental Se to Se2− and cupric Cu2+ to Cu+ to directly form the ternary compound. The growth of CuInSe2 nanoplates derived from the ethylenediamine-assisted solution involved in the formation of intermediate phase CuSe with lamellar morphology and subsequently a transformation of the CuSe phase into CuInSe2 phase by gradual reduction of cupric Cu2+ to cuprous Cu+, In3+ and active Se2− participation at growing lattice sites.

Polyol process synthesis of metal selenide nanomaterials and their photovoltaic application

A mixed solvent of monoethanolamine and thioglycolic acid is successfully used to dissolve Se powder to prepare a highly reactive and soluble Se solution at room temperature in air. The as-prepared Se solution is very stable for more than half a year without any observed precipitation even in air. We used the Se precursor solution to synthesize various metal selenide nanomaterials such as Sb2Se3 nanorods, CuSe nanoplates and CuInSe2 nanocrystals by using a facile and environmentally-friendly triethylene glycol process. The structure, morphology, chemical composition and optical properties of the synthesized metal selenide nanomaterials are characterized. Moreover, the CuInSe2 nanocrystals are used to prepare ethanol-based colloidal ink and then deposited thin films by a dip-coating process. The synthesized CuInSe2 nanocrystal thin films are annealed at 550 °C in a selenizing atmosphere. A power conversion efficiency of 2.65% has been achieved by using the CuInSe2 thin films after selenization as a light-absorbing layer under AM 1.5 illumination.

Synthesis and Photo-Response of CuS Thin Films by an In Situ Multi-Deposition Process at Room Temperature: A Facile and Eco-Friendly Approach

Uniform hexagonal covellite CuS thin films were deposited at room temperature by an in situ solution chemical reaction using copper precursor solid films as cationic source and ammonium sulfide ethanol solution as anionic reaction medium. We investigated the influence of both ethanolamine and butanol contents used in copper nitrate/ethylene glycol monomethylether (EGME) cationic solution for the preparation of copper precursor solid films, deposition cycle numbers and annealing treatment of the as-grown thin films by X-ray diffraction (XRD), FESEM, energy dispersive X-ray fluorescence EDX, transmission electron microscopy–Selected area electronic diffraction (TEM–SAED), atomic force microscopy (AFM) and ultraviolet-visible-near-infrared (UV-Vis–NIR) measurements. Photo-response of the CuS thin films was characterized by linear sweep voltammetry. The deposited CuS thin films were used to sensitize TiO2 anodes for solar cell application. The results showed that the CuS films had two-dimension oriented, half-sheet shaped growing morphology standing disorderly but vertically to substrates, and the calculated texture coefficient TC(102) verified that the half-sheet shaped crystallites had (102) plane orientation. This in situ multi-deposition process had an average deposited rate of 9 nm per cycle, and a self-perfect function to grow smooth, uniform and 2D oriented morphology with increase in the dip-cycle numbers. The photocurrent density was 14.5 Ma/cm2 at 1 V versus Ag/AgCl electrode for the annealed CuS thin films. CuS-sensitized TiO2 solar cells had a maximum conversion efficiency of 0.224%.