title: Solvothermal synthesis of zincblende and wurtzite CuInS2 nanocrystals and their photovoltaic application.
abstract: We report a simple solvothermal synthesis approach to the growth of CuInS(2) nanocrystals with zincblende- and wurtzite-phase structures. Zincblende nanocrystals with particle sizes of 10-20 nm were produced using oleylamine as the solvent. When ethylenediamine was used as the solvent, similarly sized wurtzite nanocrystals with some degree of particle aggregation were formed. Use of a mixture of these solvents gave products with mixed phases including some polyhedral nanostructures. The crystal phases of these nanocrystals were carefully determined by X-ray diffraction and transmission electron microscopy analysis. All the samples exhibit strong absorption from the entire visible light region to the near-infrared region beyond 1300 nm. Pure-phase zincblende and wurtzite CuInS(2) nanocrystals were employed as ink in the fabrication of solar cells. The spray-coated nanocrystal layer was subjected to a selenization process. A power conversion efficiency of ~0.74% and a good external quantum efficiency profile over broad wavelengths have been measured. The results demonstrate that wurtzite and zincblende CuInS(2) nanocrystals may be attractive precursors to light-absorbing materials for making efficient photovoltaic devices.
authors.affiliation: Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan.
authors.forename: Wan-Chen
authors.initials: WC
authors.lastname: Huang
authors.forename: Chih-Hsiao
authors.initials: CH
authors.lastname: Tseng
authors.forename: Shu-Hao
authors.initials: SH
authors.lastname: Chang
authors.forename: Hsing-Yu
authors.initials: HY
authors.lastname: Tuan
authors.forename: Chien-Chih
authors.initials: CC
authors.lastname: Chiang
authors.forename: Lian-Ming
authors.initials: LM
authors.lastname: Lyu
authors.forename: Michael H
authors.initials: MH
authors.lastname: Huang