CsPbBr perovskite quantum dots (PQDs)/ethylene vinyl acetate (EVA) composite films were prepared via a one-step method; on the basis of this, both supersaturated recrystallization of CsPbBr PQDs and dissolution of EVA were realized in toluene. The prepared films display outstanding green-emitting performance with high color purity of 92% and photoluminescence (PL) quantum yield of 40.5% at appropriate CsPbBr PQD loading. They possess long-term stable luminescent properties in the air and in water, benefiting from the effective protection of CsPbBr PQDs by the EVA matrix. Besides, the prepared CsPbBr PQDs/EVA films are flexible enough to be repeatedly bent for 1000 cycles while keeping unchanged the PL intensity. The optical properties of the CsPbBr PQDs/EVA films in white light-emitting diodes were also studied by experiments and theoretical simulation. Overall, facile preparation process, good long-term stability, and high flexibility allow our green-emitting CsPbBr PQDs/EVA films to be applied in lighting applications and flexible displays.

It is demonstrated that Sr5(PO4)3Cl:Eu2+ blue-emitting phosphor features good thermal ability, high color purity and is a suitable blue-emitting candidate for the application in near-UV w-LEDs.

In this paper, we carry out the theoretical spectral optimization and perform experiments by varying temperature and electrical current primarily on one-phosphor-coated three-hump white light-emitting diode (LED) for healthy indoor or outdoor lighting by using the genetic algorithm (GA). White light with low circadian action factor (CAF) is propitious for bedroom lighting to help people relax and to promote sleep, whereas high CAF white light is beneficial for increasing working efficiency in the working place. We obtain low CAF or high CAF according to different application occasions (such as bedroom lighting or office lighting), good Commission Internationale de L'Eclairage color rendering index (R a ) or Illumination Engineering Society of North America color fidelity index (R f ), and color gamut index (R g ) or other color performances, and possibly high luminous efficacy of radiation (LER, K ) at various correlated color temperatures (CCTs) from 2700 to 6500 K. For instance, in the case of one-phosphor-coated three-hump white LEDs at CCT = 3000 K, the low CAF as 0.264 (R a = 80, R f = 77, R g = 103, and K = 350.0 lm/W) can be achieved, whereas that of standard light at the same CCT is 0.407. In addition, we also compare four types of three-hump white LEDs in performances of circadian action, luminous efficacy of radiation (LER), and color rendering. This paper can help both industry and academia understand the application of three-hump white LEDs in the healthy indoor or outdoor lighting.

Poor stability always restricts the application of all-inorganic perovskite quantum dots (PQDs). Herein, 2D hexagonal boron nitride (h-BN) nanosheets were firstly utilized to stabilize CsPbBr3 PQDs through a facile heterogeneous nucleation–growth process at room temperature. In synthesized h-BN/CsPbBr3 PQD nanocomposites, cubic CsPbBr3 PQDs adhere on h-BN nanosheet surfaces, benefiting from the high specific surface area and abundant mesopores of 2D nanosheets. The nanocomposites prepared at optimized loading of h-BN nanosheets and reaction time display good green-emitting performance with a narrow full width at half maximum of ∼20.0 nm and high color purity of 92.0%. Unique 2D structure and excellent thermal conductivity of h-BN nanosheets endow the h-BN/CsPbBr3 PQD nanocomposites with significantly enhanced humidity stability and thermal stability. The white light-emitting diodes (LEDs) assembled with green-emitting nanocomposites, a blue chip, and a commercial red phosphor possess a low correlated color temperature of 4190 K, color-rendering index of 76, and high luminous efficacy of 57 lm/W. Further, the color gamut of the synthetic white light based on blue-emitting h-BN/CsPbBr1.5Cl1.5 PQDs, green-emitting h-BN/CsPbBr3 PQDs, and red-emitting h-BN/CsPbBr1.2I1.8 PQDs is 114% of the National Television System Committee standard. This work paves a new way for utilizing 2D nanomaterials to synthesize stable all-inorganic PQDs for white LEDs and displays.

A solution for multi-functional indoor light sources is proposed to achieve the new concept of healthy lighting. A remotely controllable light source that embodies a quadruple-chip light-emitting diode and driven by pulse-width-modulation currents is designed. Therefore, spectral power distributions (SPDs) of the light source can be readily controlled. An algorithm, namely the optical power ratio algorithm, is developed to select all suitable SPDs adapted for various applications. Principles of selection are based on those traditional visual indices, as well as on some non-visual parameters such as circadian action factor, circadian efficacy of radiation and circadian illuminance. We investigate in detail the correlation among these parameters and provide SPDs with both decent visual and non-visual performances for three typical cases. The study suggests some fundamental principles for designing healthy light sources, and can be regarded as a guide for designing indoor light sources of the next generation.