Solid State Lighting
Solid-state lighting (SSL) uses light emitting diodes (LEDs), organic light emitting diodes (OLED), or polymer light emitting diodes (PLED) as sources of illumination rather than electrical filaments, plasma (used in arc lamps such as fluorescent lamps), or gas. Solid state refers to emission of light from a solid block of semiconductor rather than from a vacuum of gas tube as in the case of traditional incandescent light bulbs and fluorescent lamps. Unlike incandescent light, SSL creates visible light with reduced heat generation or parasitic energy dissipation, similar to that of fluorescent lighting. Its solid-state nature provides for greater resistance to shock, vibration, and wear which increases its lifespan significantly. Solid-state lighting is often used in modern vehicle lights, train marker lights, remote controls and traffic lights.
Among the many potential applications of white LEDs, SSL has recently commanded much attention as a cost-competitive energy efficient alternative to conventional electrical lighting. Ocean NanoTech and collaborators have studied novel white QD-LED configuration where a layer of yellow-emitting CdSe–ZnS core/shell QDs was deposited over a thin film of a blue-emitting polymer, creating a simple, bi-layer electroluminescent device that generates binary complementary white light. By optimizing the thickness of the QD layer, we achieved stable and bright white QD-LEDs operating over a wide range of bias. The onset voltage of the device was as low as 3.15 V, and the maximum brightness was measured to be 2600 cd/m2 (Figure ). We are now working on the improvements of the power efficiency and lifetime of our white QD-LEDs.