White Light-Emitting Electrochemical Cells Based on the Langmuir–Blodgett Technique

Light-emitting electrochemical cells (LECs) showing a white emission have been prepared with Langmuir–Blodgett (LB) films of the metallosurfactant bis­[2-(2,4-difluorophenyl)­pyridine]­[2-(1-hexadecyl-1H-1,2,3-triazol-4-yl)­pyridine]­iridium­(III) chloride (1), which work with an air-stable Al electrode. They were prepared by depositing a LB film of 1 on top of a layer of poly­(N,N′-diphenyl-N,N′-bis­(4-hexylphenyl)-[1,1′-biphenyl]-4,4′-diamine (pTPD) spin-coated on indium tin oxide (ITO). The white color of the electroluminescence of the device contrasts with the blue color of the photoluminescence of 1 in solution and within the LB films. Furthermore, the crystal structure of 1 is reported together with the preparation and characterization of the Langmuir monolayers (π–A compression isotherms and Brewster angle microscopy (BAM)) and LB films of 1 (IR, UV–vis and emission spectroscopy, X-ray photoelectron spectroscopy (XPS), specular X-ray reflectivity (SXR), and atomic force microscopy (AFM)).

本研究制备了发射白光的发光电化学池（light-emitting electrochemical cells, LECs），其活性层为金属表面活性剂双[2-(2,4-二氟苯基)吡啶][2-(1-十六烷基-1H-1,2,3-三唑-4-基)吡啶]氯化铱(III)(1)的朗缪尔-布洛杰特（Langmuir–Blodgett, LB）薄膜，该器件采用空气稳定铝电极即可正常工作。该器件的制备流程为：将化合物1的LB薄膜沉积在旋涂于氧化铟锡(indium tin oxide, ITO)基底上的聚(N,N′-二苯基-N,N′-双(4-己基苯基)-[1,1′-联苯]-4,4′-二胺)(pTPD)层表面。该器件的电致发光呈白色，与化合物1在溶液及LB薄膜中的光致发光蓝色形成鲜明反差。此外，本文还报道了化合物1的晶体结构，以及化合物1的朗缪尔单分子层（π-A压缩等温线与布鲁斯特角显微镜(Brewster angle microscopy, BAM)表征）和LB薄膜的制备与表征：表征手段包括红外(IR)、紫外-可见(UV–vis)及发射光谱、X射线光电子能谱(X-ray photoelectron spectroscopy, XPS)、镜面X射线反射率(specular X-ray reflectivity, SXR)与原子力显微镜(atomic force microscopy, AFM)分析。