ABSTRACT
CaSnO3: Pr3+ phosphor for new application in temperature sensing was investigated. CaSnO3: 0.3%Pr3+ had distorted orthorhombic perovskite structure and Pr3+ occupied Ca2+ sites due to their similar ionic radii. CaSnO3: 0.3%Pr3+ had spherical particles with mean size of 0.816 µm. The electric dipole-dipole interaction could explain the concentration quenching mechanism. The chromaticity coordinates were (0.1324, 0.3847), located in greenish-blue region and the average afterglow decay time was 60.2 s for CaSnO3: 0.15%Pr3+, which had potential applications for LED and emergency lighting. CaSnO3: 0.3%Pr3+ had the activated energy of 0.380 eV. The maximum relative temperature sensitivity for CaSnO3: 0.3%Pr3+ was 7.57% K-1 at 298 K and relative sensitivity was as high as 6722.76/T2 K-1, which was better than that of most Pr3+ doped phosphors and had potential application in temperature sensing. Moreover, the possible luminescence and long afterglow mechanisms and thermal quenching process of 3P0 level through IVCT state were proposed.
ABSTRACT
A novel facile room-temperature, hexamethyldisilazane (HMDS)-mediated strategy is demonstrated for the synthesis of all-inorganic perovskite colloidal nanocrystals (NCs). As a unique reaction-triggering and morphology-directing agent, HMDS is introduced for the first time to trigger the room-temperature reaction for generating perovskite NCs with controlled morphology and optical properties. Particularly, the stability of the resulting NCs is greatly enhanced due to the surface modification by hydrophobic -CH3 groups from HMDS. The typical CsPbBr3 perovskite NCs films are highly stable without significant decrease in photoluminesence (PL) intensity after being exposed to 60% relative humidity for 720â¯h. Moreover, no noticeable change of phase and morphology occurs even after 100â¯days of exposure. The representative CsPbBr3 NCs are employed in a prototype white-light-emitting diodes (WLEDs) on 365â¯nm commercial GaN chip. The present strategy provides a facile and versatile route not only to control the morphology and optical properties of perovskites nanomaterials at room temperature but also enhance their stability, which will bring promising potential application for optoelectronics.
ABSTRACT
Mn4+-Doped oxide phosphors are under intensive investigation owing to their low manufacture cost and attractive luminescent features for indoor plant cultivation applications. However, it is still a challenge to develop Mn4+-doped oxides with high luminescence efficiency and thermal stability. Herein, Mn4+-Mg2+ pairs are incorporated into a CaGdAlO4 host to reduce non-radiative channels formed by Mn4+-Mn4+-O2- clusters. The photoluminescence and quantum efficiency are significantly enhanced after the introduction of Mg2+ ions to the host. A prolonged Mn4+ decay time is also obtained from the Mn4+/Mg2+ co-doped samples. Intense red emission with a narrow peak at 712 nm due to the 2Eg â 4A2g transition of Mn4+ ions is observed under 335 nm excitation. LEDs fabricated by coating the synthesized phosphor on a 365 nm near-UV chip exhibit an intense deep-red emission with CIE chromaticity coordinates of (0.712, 0.285). The results indicate Mn4+/Mg2+ co-doped CaGdAlO4 phosphors may be applicable to plant cultivation fields.
ABSTRACT
Two novel asymmetrical push-pull small molecules have been synthesized successfully, consisting of triphenylamine and diketopyrrolopyrrole as a fundamental dipolar D-π-A structure with ethynylbenzene as the π-bridge. TPATDPPCN end-capped with cyanophenyl exhibits a low optical band gap of 1.65 eV, and an impressive PCE of 5.94% has been achieved.
ABSTRACT
Two novel D-π-A-π-D structured small molecules composed of benzothiadiazole and triphenylamine were designed and synthesized. with cyano on the π-bridge exhibited a deep HOMO energy level, resulting in an impressive V(OC) of up to 1.04 V with a PCE of 3.85%, while non-cyano substituted yielded a V(OC) of 0.94 V and a PCE of 1.99%.
