Pay-Yu Lee

Rinsing Effects on Successive Ionic Layer Adsorption and Reaction Method for Deposition of ZnO Thin Films

This study investigates different rinsing processes using a successive ionic layer adsorption and reaction (SILAR) method to deposit ZnO thin films. Rinsing in ultrasonic-assisted deionized (DI) water reveals thin films with better adsorptive attraction compared with a traditional SILAR method because the former can remove the loosely attached ZnO and unreacted Zn(OH) 2 grains. In this case, the ZnO films appear as large pellets and white particles with low transparency. The structure and transparency of ZnO thin films can be significantly improved by using ultrasonic irradiation and rinsing in ethylene glycol rather than rinsing in DI water. The obtained ZnO films exhibited were more smooth, compact, and diaphanous, and the transparencies of ZnO films reached as high as 90% in the visible-light wavelength region. Furthermore, when the rinsing temperature of ethylene glycol was increased from 95 to 125°C, the ZnO films appeared to have finer grain size, higher transparency, and lower oxygen vacancies. Mechanism analysis indicated that the ethylene glycol acts as a dispersing agent to reduce ZnO agglomeration and the higher rinsing temperature enhances the decomposition capability of Zn(OH) 2 .

Synthesis of CZTSe Nanocrystal Prepared by a Facile Route in Coordinating Solvent From Elemental Sources

This paper reports the preparation of Cu2 ZnSnSe4 (CZTSe) nanocrystals from elemental sources through the application of various coordinating solvents. The CZTSe nanocrystals were synthesized by mixing metals in oleylamine (OLA) and isophorondiamine (IPDA) at a ratio of 1:3 as well as a Se solution in trioctylphosphine (TOP) under N2 flow at atmospheric pressure at a reaction temperature of 235 °C. X-ray diffraction and Raman spectroscopy were used to track the reaction mechanisms associated with various solvents. A growth mechanism, distinct from that associated with TOP/OLA, promoted the formation of nanoparticles and improved the reactivity provided by the addition of IPDA solvent through double N-chelation. The reaction mechanism involved in stannite Cu2 ZnSnSe4 phase crystallization from Cu2 SnSe3 and ZnSe is supported by theoretical analysis. The monodispersed CZTSe nanocrystals are polycrystalline and 20-30 nm in size. Optical measurements revealed a direct band gap of 1.42 eV. This study presents a relatively simple, low cost coordinating solvent route for the synthesis of CZTSe nanoparticles, applicable to the fabrication of low-cost thin-film solar cells.