High-performance white-light-emitting diodes (WLEDs) are regarded as a promising next-generation solid-state light source. However, a low-color-rendering index (CRI), consumption of rare-earth elements, and inevitable self-absorption remain the major challenges for high-performance WLEDs. Here, lead-doped Cs 3 Cu 2 Br 5 nanocrystals (NCs) with a zero-dimensional structure are prepared to facilitate stable and intrinsic white-light emission (IWE) without phosphors and other compositions. The lead dopants are expected to be centers of isolated [PbBr 6 ] octahedrons, in which self-trapped excitons originating from distorted octahedra can form. Subsequently, a broadband blue photoluminescence (PL) from the Cs 3 Cu 2 Br 5 and a broadband red PL from the lead doping are observed, exhibiting intrinsic white-light emission overall. The doped Cs 3 Cu 2 Br 5 NCs are then employed to fabricate WLEDs, which possess a high CRI of 98 and an excellent 200-h operating stability.
The lighting market has been dominated by light emitting diodes (LEDs), which not only need Ga for wafer production, but also consume abundant non-sustainable rare-earth elements such as Y, Ce and Eu. Hybrid-LED technology using organic downconversion materials (ODMs) is a promising candidate technology to save the rare-earth elemental resources. However, it is still a challenge to fabricate hybrid-LED devices with a high color rendering index (CRI), lumen efficiency and long lifetime at the same time. Herein, highly dispersible perylene diimides are synthesized in short routes and dispersed into a polymer matrix at high temperature to produce low cost light ODMs. Cold to warm white LED lamps with a CRI up to 92 can be fabricated with the ODMs. In particular, a warm white lamp with the same high CRI and efficiency up to 82 lm W−1 is obtained. It is comparable to all inorganic warm white LEDs with such a high CRI. By applying our OMDs, an approach for highly efficient yellow LED lamps, which can improve efficiency by 66% to 153 lm W−1 compared with the present method, is illustrated. More importantly, incorporating a remote phosphor configuration (RPC) effectively improves the lifetime of ODMs superior to 2870 h, extrapolated to 6000 h maintaining 70% of the original fluorescence efficiency after continuous operation in an ambient environment. This approach could be a quite simple protocol paving the way for the practical application of hybrid-LED lamps.
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