Light-Emitting Electrochemical Cells Based On Color-Tunable Inorganic Colloidal Quantum Dots

Large-area, ultrathin light-emitting devices currently inspire architects and interior and automotive designers all over the world. Light-emitting electrochemical cells (LECs) and quantum dot light-emitting diodes (QD-LEDs) belong to the most promising next-generation device concepts for future flexible and large-area lighting technologies. Both concepts incorporate solution-based fabrication techniques, which makes them attractive for low cost applications based on, for example, roll-to-roll fabrication or inkjet printing. However, both concepts have unique benefits that justify their appeal. LECs comprise ionic species in the active layer, which leads to the omission of additional organic charge injection and transport layers and reactive cathode materials, thus LECs impress with their simple device architecture. QD-LEDs impress with purity and opulence of available colors: colloidal quantum dots (QDs) are semiconducting nanocrystals that show high yield light emission, which can be easily tuned over the whole visible spectrum by material composition and size. Emerging technologies that unite the potential of both concepts (LEC and QD-LED) are covered, either by extending a typical LEC architecture with additional QDs, or by replacing the entire organic LEC emitter with QDs or perovskite nanocrystals, still keeping the easy LEC setup featured by the incorporation of mobile ions.