Highly Emissive and Color‐Tunable CuInS2‐Based Colloidal Semiconductor Nanocrystals: Off‐Stoichiometry Effects and Improved Electroluminescence Performance

• DOI: 10.1002/adfm.201102496
• Publication Date: 2012-03-04T09:41:01Z
• Authors: Bingkun Chen; Haizheng Zhong; Wenqing Zhang; Zhan'ao Tan; Yongfang Li; Cairan Yu; Tianyou Zhai; Yoshio Bando; Shengyi Yang; Bingsuo Zou
• Keywords: 02 engineering and technology; 0210 nano-technology; 7. Clean energy

AbstractThe off‐stoichiometry effects and gram‐scale production of luminescent CuInS2‐based semiconductor nanocrystals, as well as their application in electroluminescence devices are reported. The crystal structures and optical properties of CuInS2 nanocrystals can be significantly influenced by controlling their [Cu]/[In] molar ratio. A simple model adapted from the bulk materials is proposed to explain their off‐stoichiometry effects. Highly emissive and color‐tunable CuInS2‐based NCs are prepared by a combination of [Cu]/[In] molar ratio optimization, ZnS shell coating, and CuInS2–ZnS alloying. The method is simple, hassle‐free, and easily scalable to fabricate tens of grams of nanocrystal powders with photoluminescence quantum yields up to around 65%. Furthermore, the performance of high‐quality CuInS2‐based NCs in electroluminescence devices is examined. These devices have lower turn‐on voltages of around 5 V, brighter luminance up to approximately 2100 cd m−2 and improved injection efficiency of around 0.3 lm W−1 (at 100 cd m−2) in comparison to recent reports.