Light sensors are widely used to monitor light intensities, for instance in medical applications, in agriculture or for conservation of art. Most of these sensors are electronic devices that record continuously but applications that only require information of integrated intensities, measured over a long time, could greatly benefit from an integrating dosimeter that does not require a power supply. In this work a wireless and quantitative light dosimeter is presented based on SrAl 2 O 4 :Eu 2+ ,Sm 3+ , a phosphor that exhibits stable energy storage upon exposure to blue and ultraviolet light. It is shown that a forward electron transfer from europium to samarium can be induced under illumination with blue or ultraviolet light while the reverse electron transfer can be achieved by illuminating the phosphors with green to infrared light. This reverse transfer is accomplished through excitation of the divalent samarium and results in bright, green optically stimulated luminescence. The stable energy storage, in combination with the possibility for optical read-out, makes SrAl 2 O 4 :Eu 2+ ,Sm 3+ ideally suited to be used as an integrating light dosimeter for monochromatic to broadband light, from the ultraviolet to the near infrared. To demonstrate this, a proof of concept dosimeter was developed in which this phosphor was successfully used to measure average daylight intensities.

There are several key requirements that a very good LED phosphor should meet, i.e., strong absorption, high quantum efficiency, high colour purity, and high luminescence quenching temperature. The reported Rb2Bi(PO4)(MoO4):Eu3+ phosphors have all these properties. The Rb2Bi(PO4)(MoO4):Eu3+ phosphors emit bright red light if excited with near-UV radiation. The calculated colour coordinates show good stability in the 77–500 K temperature range. Moreover, sample doped with 50% Eu3+ possesses quantum efficiency close to unity. Besides the powder samples, ceramic disks of Rb2Eu(PO4)(MoO4) specimen were also prepared, and the red light sources from these disks in combination with near-UV emitting LED were fabricated. The obtained results indicated that ceramic disks efficiently absorb the emission of 375 and 400 nm LED and could be applied as a red component in phosphor-converted white LEDs.

Rare-earth-doped GdPO4 nanoparticles have recently attracted much scientific interest due to the simultaneous optical and magnetic properties of these materials and their possible application in bio-imaging. Herein, we report the hydrothermal synthesis of GdPO4:Eu3+ nanoparticles by varying different synthesis parameters: pH, <Gd>:<P> molar ratio, and Eu3+ concentration. It turned out that the Eu3+ content in the synthesized nanoparticles had little effect on particle shape and morphology. The synthesis media pH, however, has showed a pronounced impact on particle size and distribution, i.e., the nanoparticle length can be adjusted from hundreds to tens of nanometers by changing the pH from 2 to 11, respectively. Increasing the <Gd>:<P> molar ratio resulted in a decrease in nanoparticle length and an increase in its width. The temperature-dependent measurements in the 77–500 K range revealed that the GdPO4:50%Eu3+ sample maintains half of its emission intensity, even at room temperature (TQ1/2 = 291 ± 19 K).

Novel and highly thermally stable K2Bi(PO4)(MoO4):Sm3+ phosphors were prepared and used to produce pcLEDs for horticulture and general lighting application.