The roles of amorphous Si nanoparticles in light-emitting diodes (LEDs) based on Er-doped Si(1+x)O(2) films (x representing the degree of Si content, and varying widely from 0 to 4.50) have been investigated. In the aspect of the LEDs' electrical performance, it was found that the incorporation of Si nanoparticles facilitates the electrical conductivity of the films by improving the carrier mobility. With x increasing from 0 to 4.50, the mobility increases monotonically up to 5 times. The efficiency of Er(3+) electroluminescence (EL) at 1.54 µm can be enhanced by as much as 160 times when the degree of Si content x is 2.00, coincident with the value at which the rate of mobility increasing versus x slows down. The fact that the maximum of EL efficiency and the slowing down of the rate of increase of mobility occur at the same x value can be explained by coalescence of Si nanoparticles starting at x = 2.

Alloy core/shell CdZnS/ZnS quantum dots (QDs) are emerging as robust candidates for light-emitting diodes (LEDs), however the emission range of the current CdZnS/ZnS is quite limited, ranging from 390 to 470 nm. It still remains a challenging task to construct white LEDs based on current CdZnS/ZnS system. Here, a versatile ZnSe with a moderate band gap is introduced onto the CdZnS core. The ZnSe shell, on one hand, can passivate the core surface which leads to bright emissions. On the other hand, it is essential in extending the emission to red region so that the emission wavelengths of CdZnS/ZnS and CdZnS/ZnSe QDs can cover the whole visible region, which is very important for white LED applications. Two- and four-hump QD-based LEDs are computationally and experimentally investigated. Results show that four-hump quantum dot light-emitting diodes (QLED) have better performances than the two-hump one, in the luminous and the vision properties. The fabricated white LEDs (WLEDs) based on CdZnS/ZnS and CdZnS/ZnSe QDs exhibits a scotopic/photopic ratio (S/P) ratio as high as 2.52, which exceeds the current limit of 2.50 by common lighting technologies, a color rendering index of 90.3, a luminous efficacy of optical radiation of 460.78 lumen per unit optical power, and a correlated color temperature of 5454 K. These results suggest that CdZnS/ZnS and CdZnS/ZnSe quantum dots serving as emitters hold great promise for the next-generation white light source with better S/P ratio.

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Development of a novel fluorescence enhancement probe for detection of Sn2+ in organisms, with high selectivity and sensitivity, is of great interest but remains a great challenge.