Smart Flexible Quantum Dot Lighting

cQD are attracting significant interest as the key components for next-generation smart displays/lightings, photo detectors and image sensors, and solar cells. This is because they show excellent and unique physical properties such as i) high sensitivity and quantum efficiency, ii) excellent colour gamut with narrow emission (absorption) bandwidths, iii) colour tunability/band gap engineering through size control, iv) high photostability and v) high air stability as they are based on inorganic materials. Therefore, since the latest results on cQD LEDs and image sensors/photodetector have demonstrated the possibility of integration of cQD optoelectronics with current semiconducting technologies, the pace of research in the cQD area has been accelerated dramatically and an increasing number of research groups and companies are currently active in this area worldwide. The investigators expect that cQD LED will replace current technologies through: (1) Superior reliability of the inorganic structure in an almost air barrier free architecture w.r.t OLED (WVTR of 10-6 g/m2/day), (2) Lower power consumption and low product cost, 60 and 50 % less than current OLED, respectively, and (3) Colour purity of 110% or greater compared to typically 80% for OLED. This project will address will enhance the current state of the art to achieve cost reduction through using continuous, as opposed batch, cQD synthesis, mono layer resin free processing, all inorganic interface materials such as ETL (electron transport layer) and HTL (hole transport layer), device integration and packaging for EL cQD LED, with Cd-free cQDs for smart lighting and displays. The project proposed builds upon research established in the investigators' groups in Cambridge and Oxford. We are well equipped with facilities for pilot fabrication using technologies which will underpin the commercialisation of cQD LED based lighting/displays. The final deliverable will be energy efficient 4" active devices with predictable life times, and sustainable high brightness for flexible smart lighting. The elements of the smart light which will include colour hue and brightness control based on active matrix switching of pixels will also be applicable to displays, but without the same high pixel definition. We shall explore the design and synthesis of Cd-free cQDs with the core/shell structures using continuous flow production methods which can then be incorporated into active devices. Key to successfully implementing devices are the scalable production of high quality cQDs with specific surface passivation and functionalisation which limit the effects of impurities and defects and produce high quality thin films with well understood interfaces. In this project we will use scalable production techniques that can be transferred to in-line process for mass production. We shall focus on the manufacturing and processing aspects to create mono layer-controlled cQD films with entire close-packed and almost void free structure using dry-transfer printing methods. This will enhance efficiency and reliability of film for the desired mode of devices. Interface control based on a monolayer level layer-by-layer transfer process will be employed in order to obtain highly uniform monolayers which can be expanded to multilayer stacked film processing including interface layers. The interface materials for emissive cQD film with inorganic HTL and ETL layer for EL devices will also be designed and fabricated at the device integration step (WP 2-3). Driving electronics using TFTs will be designed for reliable and stable operation. Industrial partners in the supply chain for smart flexible lighting production, are: CDT Ltd for materials, lighting, metrology; CPI Ltd, Dupont-Teijin Films UK for flexible films for lighting; Emberion UK, Dyson, FlexEnable, Samsung UK for device processing, and system integration; Aixtron UK for TCF; Nanoco and Merck as materials suppliers and EAB members.