Producing white light using near-UV LEDs requires the development of new phosphors, as well as the modification of certain existing ones. In this review, we discuss the luminescent properties of potential phosphors: oxides, silicates, phosphates and nitrides. We evaluate phosphors that employ 4f-5d transitions, line emission, the use of sensitizers and transition metal elements. We include information on the optical transitions and how these can limit the selection of a composition.

During the past few years there has been a significant progress in adapting the properties of non-Cd quantum dots (QDs) for lighting applications. It includes synthesis of novel materials, improvement of quantum efficiency and thermal stability, and most importantly, manufacturability on a scale large enough to meet the needs of the lighting industry. In this paper, we review the characteristics of three most mature non-Cd QD material systems, InP, CuInS2 and doped ZnS/ZnSe, from the perspective of lighting applications. Of these three systems, the InP-based QDs with core/shell structure are now available with quantum efficiency (QE) comparable to the best performing CdSe QDs, and in quantities large enough to meet the lighting needs. The CuInS2 QDs have also emerged as another non-toxic alternative to CdSe QDs but they need significant development to be comparable to InP and CdSe QDs.

As the lighting industry transitions from traditional technologies to solid state lighting (SSL), it appears that the most preferred way to generate white light using SSL technology has been to use phosphor-converted light emitting diodes (pc-LEDs). There has been considerable debate in the literature whether near-UV LEDs or blue LEDs should be used to excite phosphors for white light. Quite often, in the phosphor literature, the efficiencies of LEDs from 365 nm to 470 nm are somewhat neglected in this debate. In this paper, we have provided data on external quantum efficiency of InxGa1-xN LEDs over the above spectral range, and use these data together with phosphor performance to compare near-UV and blue based approaches to making white light pc-LEDs. We also use simulations to discuss white light blends at two different correlated color temperatures (3000 K and 4000 K) for both LED configurations.

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