A novel integrated circuit for driving LED lighting has been proposed, designed and fabricated. Besides the typical parts of LED driver, an integral part was added at the output terminal of error amplifier in the driv...A novel integrated circuit for driving LED lighting has been proposed, designed and fabricated. Besides the typical parts of LED driver, an integral part was added at the output terminal of error amplifier in the driver. In this way, a novel average current mode can be set up to take the place ordinary peak current control mode. In addition, a BUCK low-level topology was adopted, too. It can be used to drive up to eight 1 W HB LED lights with 350 mA constant current. In this way, the LED driver displays high performance, in which output current with less 1% error and total efficiency as high as 96%. The feasibility of the design has been verified by actual measurement on the fabricated chip.展开更多
With andromonoecious<i><span> Momordica charantia </span></i><span>L.</span><span> </span><span>(bitter gourd) as material, three light qualities</span><s...With andromonoecious<i><span> Momordica charantia </span></i><span>L.</span><span> </span><span>(bitter gourd) as material, three light qualities</span><span> </span><span>(50 μmol·m</span><sup><span style="vertical-align:super;">-2</span></sup><span>·s</span><sup><span style="vertical-align:super;">-1</span></sup><span>) including white LED light</span><span> </span><span>(WL), blue monochromatic light (B,</span><span> </span><span>465 nm), and red monochromatic light (R, 650 nm) were carried out to investigate their effects on seed germination, physiological and biochemical parameters, sex differentiation and photosynthetic characteristics of bitter gourd. The results showed that compared to the WL treatment, the R treatment significantly promoted seed germination, seedling height elongation and soluble sugar content, the B treatment significantly increased seedling stem diameter, reducing sugar content and soluble protein content, the R and B treatments both significantly reduced sucrose content, but their POD activity showed no significant difference. Compared with the R treatment, the B treatment significantly increased the total female flower number and female flower nod ratio in 30 nods of main stems. The study of photosynthetic characteristics found that the R and B treatments could effectively increase the </span><span>stomata</span><span>l conductance (GS) of leaves, significantly improved the net photosynthetic rate</span><span> </span><span>(Pn) compared to the WL treatment, and the effect of the B treatment was better. Compared to the R and WL treatments, the B treatment increased the maximum photosynthetic rate (P</span><sub><span style="vertical-align:sub;">max</span></sub><span>),</span><span> </span><span>apparent quantum efficiency</span><span> </span><span>(AQE) and light saturation point</span><span> </span><span>(LSP), and reduced the dark respiration rate (Rd) and light compensation point</span><span> </span><span>(LCP) of the leaves. Fit light response curves showed that the adaptability and utilization of weak light in bitter gourd were middle or below, but it showed higher adaptability and utilization of strong light. Thus, it suggests that </span><i><span>Momordica charantia</span></i><span> is a typical sun plan with lower Rd. In summary, it is concluded that blue light has a positive effect on the seed germination, seedling growth, sex differentiation and improving the photosynthetic performance, and this will lay the foundation for artificially regulating optimum photosynthesis using specific LEDs wavelength, and help to elucidate the relationship how light quality influences the sex differentiation of plant.</span>展开更多
Perovskite light emitting diodes(PeLEDs)have attracted considerable research attention because of their external quantum efficiency(EQE)of>20%and have potential scope for further improvement.However,compared to red...Perovskite light emitting diodes(PeLEDs)have attracted considerable research attention because of their external quantum efficiency(EQE)of>20%and have potential scope for further improvement.However,compared to red and green PeLEDs,blue PeLEDs have not been extensively investigated,which limits their commercial applications in the fields of luminance and full-color displays.In this review,blue-PeLED-related research is categorized by the composition of perovskite.The main challenges and corresponding optimization strategies for perovskite films are summarized.Next,the novel strategies for the design of device structures of blue PeLEDs are reviewed from the perspective of transport layers and interfacial layers.Accordingly,future directions for blue PeLEDs are discussed.This review can be a guideline for optimizing perovskite film and device structure of blue PeLEDs,thereby enhancing their development and application scope.展开更多
This work applied the ultrasonic bonding to package flip chip GaN-based light emitting diodes （flip chip LEDs） on Si substrates. The effects of ultrasonic bonding parameters on the reliability of flip chip GaN-based...This work applied the ultrasonic bonding to package flip chip GaN-based light emitting diodes （flip chip LEDs） on Si substrates. The effects of ultrasonic bonding parameters on the reliability of flip chip GaN-based LED were investigated. In the sequent aging tests, samples were driven with a constant current of 80 mA for hundreds hours at the room temperature. It was found that the electroluminescence （EL） intensity variation had a large correlation to the ultrasonic power, and then to the bonding temperature and force. A high bonding temperature and ultrasonic power and a proper bonding force improved the EL intensity significantly. It was contributed to a strong atom inter-diffusion forming a stable joint at the bonding interface, The temperature fluctuation in the aging test was the main factor to generate a high inner stress forming delamination at the interface between the chip and Au bump. As a result, delamination had retarded the photons to emit out of the LED packaging and decay its EL intensity.展开更多
Solution-processed metal halide perovskites (MHPs) have received significant interest for cost-effective, high-performance optoelectronic devices. In addition to the great successes in photovoltaics, their excellent l...Solution-processed metal halide perovskites (MHPs) have received significant interest for cost-effective, high-performance optoelectronic devices. In addition to the great successes in photovoltaics, their excellent luminescence and charge transport properties also make them promising for light emitting diodes (LEDs). To achieve high-efficiency perovskite LEDs (PeLEDs), extensive efforts have been carried out to enhance radiative recombination rates by confining the electrons and holes. In addition to enhancing radiative recombination rates, it is equally important to decrease the non-radiative recombination for improving the device performance. Passivation of the defects could be an efficient way for reducing the non-radiative recombination.展开更多
文摘A novel integrated circuit for driving LED lighting has been proposed, designed and fabricated. Besides the typical parts of LED driver, an integral part was added at the output terminal of error amplifier in the driver. In this way, a novel average current mode can be set up to take the place ordinary peak current control mode. In addition, a BUCK low-level topology was adopted, too. It can be used to drive up to eight 1 W HB LED lights with 350 mA constant current. In this way, the LED driver displays high performance, in which output current with less 1% error and total efficiency as high as 96%. The feasibility of the design has been verified by actual measurement on the fabricated chip.
文摘With andromonoecious<i><span> Momordica charantia </span></i><span>L.</span><span> </span><span>(bitter gourd) as material, three light qualities</span><span> </span><span>(50 μmol·m</span><sup><span style="vertical-align:super;">-2</span></sup><span>·s</span><sup><span style="vertical-align:super;">-1</span></sup><span>) including white LED light</span><span> </span><span>(WL), blue monochromatic light (B,</span><span> </span><span>465 nm), and red monochromatic light (R, 650 nm) were carried out to investigate their effects on seed germination, physiological and biochemical parameters, sex differentiation and photosynthetic characteristics of bitter gourd. The results showed that compared to the WL treatment, the R treatment significantly promoted seed germination, seedling height elongation and soluble sugar content, the B treatment significantly increased seedling stem diameter, reducing sugar content and soluble protein content, the R and B treatments both significantly reduced sucrose content, but their POD activity showed no significant difference. Compared with the R treatment, the B treatment significantly increased the total female flower number and female flower nod ratio in 30 nods of main stems. The study of photosynthetic characteristics found that the R and B treatments could effectively increase the </span><span>stomata</span><span>l conductance (GS) of leaves, significantly improved the net photosynthetic rate</span><span> </span><span>(Pn) compared to the WL treatment, and the effect of the B treatment was better. Compared to the R and WL treatments, the B treatment increased the maximum photosynthetic rate (P</span><sub><span style="vertical-align:sub;">max</span></sub><span>),</span><span> </span><span>apparent quantum efficiency</span><span> </span><span>(AQE) and light saturation point</span><span> </span><span>(LSP), and reduced the dark respiration rate (Rd) and light compensation point</span><span> </span><span>(LCP) of the leaves. Fit light response curves showed that the adaptability and utilization of weak light in bitter gourd were middle or below, but it showed higher adaptability and utilization of strong light. Thus, it suggests that </span><i><span>Momordica charantia</span></i><span> is a typical sun plan with lower Rd. In summary, it is concluded that blue light has a positive effect on the seed germination, seedling growth, sex differentiation and improving the photosynthetic performance, and this will lay the foundation for artificially regulating optimum photosynthesis using specific LEDs wavelength, and help to elucidate the relationship how light quality influences the sex differentiation of plant.</span>
基金This work was supported by the National Natural Science Foundation of China(51775199,51735004)Natural Science Foundation of Guangdong Province(2018B030306008)the Fundamental Research Funds for the Central Universities.
文摘Perovskite light emitting diodes(PeLEDs)have attracted considerable research attention because of their external quantum efficiency(EQE)of>20%and have potential scope for further improvement.However,compared to red and green PeLEDs,blue PeLEDs have not been extensively investigated,which limits their commercial applications in the fields of luminance and full-color displays.In this review,blue-PeLED-related research is categorized by the composition of perovskite.The main challenges and corresponding optimization strategies for perovskite films are summarized.Next,the novel strategies for the design of device structures of blue PeLEDs are reviewed from the perspective of transport layers and interfacial layers.Accordingly,future directions for blue PeLEDs are discussed.This review can be a guideline for optimizing perovskite film and device structure of blue PeLEDs,thereby enhancing their development and application scope.
基金supported by the National Natural Science Foundation of China(Grant No.50675130)the National Key Technology Research and Development Program of the Ministry of Science and Technology of China(Grant No.2011BAE01B14)the Program for the New Century Excellent Talents in University(Grant No.NCET-07-0535)
文摘This work applied the ultrasonic bonding to package flip chip GaN-based light emitting diodes （flip chip LEDs） on Si substrates. The effects of ultrasonic bonding parameters on the reliability of flip chip GaN-based LED were investigated. In the sequent aging tests, samples were driven with a constant current of 80 mA for hundreds hours at the room temperature. It was found that the electroluminescence （EL） intensity variation had a large correlation to the ultrasonic power, and then to the bonding temperature and force. A high bonding temperature and ultrasonic power and a proper bonding force improved the EL intensity significantly. It was contributed to a strong atom inter-diffusion forming a stable joint at the bonding interface, The temperature fluctuation in the aging test was the main factor to generate a high inner stress forming delamination at the interface between the chip and Au bump. As a result, delamination had retarded the photons to emit out of the LED packaging and decay its EL intensity.
文摘Solution-processed metal halide perovskites (MHPs) have received significant interest for cost-effective, high-performance optoelectronic devices. In addition to the great successes in photovoltaics, their excellent luminescence and charge transport properties also make them promising for light emitting diodes (LEDs). To achieve high-efficiency perovskite LEDs (PeLEDs), extensive efforts have been carried out to enhance radiative recombination rates by confining the electrons and holes. In addition to enhancing radiative recombination rates, it is equally important to decrease the non-radiative recombination for improving the device performance. Passivation of the defects could be an efficient way for reducing the non-radiative recombination.
