Emergence of colloidal quantum-dot light-emitting technologies

This Review article summarizes the key advantages of using quantum dots (QDs) as luminophores in light-emitting devices (LEDs) and outlines the operating mechanisms of four types of QD-LED. The key scientific and technological challenges facing QD-LED commercialization are identified, together with on-going strategies to overcome these challenges. Since their inception 18 years ago, electrically driven colloidal quantum-dot light-emitting devices (QD-LEDs) have increased in external quantum efficiency from less than 0.01% to around 18%. The high luminescence efficiency and uniquely size-tunable colour of solution-processable semiconducting colloidal QDs highlight the potential of QD-LEDs for use in energy-efficient, high-colour-quality thin-film display and solid-state lighting applications. Indeed, last year saw the first demonstrations of electrically driven full-colour QD-LED displays, which foreshadow QD technologies that will transcend the optically excited QD-enhanced lighting products already available today. We here discuss the key advantages of using QDs as luminophores in LEDs and outline the operating mechanisms of four types of QD-LED. State-of-the-art visible-wavelength LEDs and the promise of near-infrared and heavy-metal-free devices are also highlighted. As QD-LED efficiencies approach those of molecular organic LEDs, we identify the key scientific and technological challenges facing QD-LED commercialization and offer our outlook for on-going strategies to overcome these challenges.