Light‐Emitting Electrochemical Cells with Polymer‐Blended InP/ZnSeS Quantum Dot Active Layer

A light-emitting electrochemical cell (LEC) is an innovative device with a simple structure wherein a mixture of a luminophore and an electrolyte is sandwiched between electrodes. Here, LECs are presented which contain an active layer composed of green-emitting InP/ZnSeS quantum dots (QDs) blended with polyvinyl carbozole p-type polymer semiconductors and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquid (IL). The blending of QDs with polymer semiconductors increases the density of holes reaching the QDs; this, in turn, leads to luminescence from QDs, which is unachievable without the presence of polyvinyl carbazole semiconductor. Moreover, the deposition of a zinc oxide nanoparticle layer onto the QD-polymer-IL active layer increases the density of electrons reaching the QDs. The composition of these materials is varied systematically for balancing the injection rates of electron versus hole into the QDs. A luminance of approximate to 632 cd m(-2) and an efficiency of >1.3 cd A(-1) are achieved.