3 results about "Quantum efficiency" patented technology

The invention relates to a multi-quantum well photovoltaic battery based on a nanometer graphite electron transmission layer, and a preparation method thereof. The battery comprises a front electrode, an anti-reflection layer, N-type silicon, P-type silicon and a back electrode, wherein a composite layer composed of graphite and semiconductor quantum dots is arranged between the anti-reflection layer and the N-type silicon. Compared to the prior art, the method is characterized in such a way that a sol method is employed, first of all, a semiconductor quantum dot colloid is prepared; under the effect of a surfactant, the graphite is uniformly dispersed to the colloid, and then, by taking the graphite as a crystal growth liquid, a uniform an ordered electron transmission layer and a semiconductor quantum dot layer are grown on the surface of a crystal silicon chip in a deposition mode. According to the invention, by use of a quantum dot impact ionization effect and a namometer effect and excellent electron separate transmission performance of nanometer graphite, the minority carrier life and the quantum efficiency of the photovoltaic battery are improved, and the nanometer graphite can improve separation and collection of electrons by the silicon solar battery, improves photoelectric currents and accordingly improve the conversion efficiency of the silicon solar battery.

The invention provides an LED (light-emitting diode) chip and a preparation method of the LED chip. The method comprises the steps of: providing a semiconductor substrate, arranging a Bragg reflecting layer, a luminous epitaxial structure, a window buffer layer and a window layer in sequence at the bottom surface of the semiconductor substrate in an epitaxial growth manner; fabricating a transparent conductive layer and a first electrode at the upper surface of the window layer in sequence; and fabricating a second electrode on the back side of the semiconductor substrate. Compared with the existing LED chip which uses a single window layer on the luminous epitaxial structure, the window buffer layer of which the material is the same as that of the window layer but the thickness is smaller than that of the window layer is added; and the epitaxial growth temperature and the epitaxial growth rate of the window buffer layer are smaller than those of the window layer. The quality defect of the window buffer layer is smaller than that of the window layer due to the epitaxial growth under a low-temperature and low-speed environment, so that the quality defect of the subsequently growing window layer is reduced, the purpose of reducing light absorption of the window layer when improving homogeneous diffusion of the current by the window layer is achieved, and further, the external quantum efficiency of the LED chip is improved.

The invention discloses a phosphorescent compound and an organic luminescent device employing the same. The phosphorescent compound comprises a structural formula 1 shown in the description and a structural formula 2 shown in the description, wherein in the structural formula 1 and the structural formula 2, Z is independently selected from the following structures: formulae shown in the description; X1 or X2 is independently selected from a N atom or C atom; either X1 or X2 is N; and Ar is independently selected from C6-C30 aryl and C2-C30 heteroaryl. According to the phosphorescent compound and the organic luminescent device employing the same, the visibility is lowered along with improvement of color purity, even, the device also expeditiously operates at low voltage when the color purity is high, the current efficiency is increased, and the luminescence efficiency is high in case of high internal quantum efficiency; and meanwhile, the phosphorescent compound is employed as a luminescent material of an organic light emitting diode device, the manufacturing process is simple, the process efficiency is high, and the production cost is low.