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Thursday, 09 April 2020
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Chemistry: Giant hyperthermal effect in Mg-doped Fe3O4 - Friday, 09 February 2018 11:36
Biology: Nanodiamonds for antibacterial implants - Monday, 02 November 2015 21:41
Ecology: Nano-products risks overexaggerated - Tuesday, 24 June 2014 11:02

10percent QD-ink solarcells titelA new article by Aqoma et al provides additional inspiration to all those working on the development of flexible low-cost high-performance solar cells.

The authors could achieve 10% conversion efficiency by employing the PbS quantum dots as the absorbing layer. Using CQD-ink, the fabrication of active layers by single-step coating and the suppression of surface trap states are achieved simultaneously. The CQD-ink photovoltaic devices achieve much higher PCEs (10.15% with a certified PCE of 9.61%) than the control devices (7.85%) owing to improved charge drift and diffusion.

This article provides new perspectives for the development of new generation of solar cells.


More information available in the Advanced Materials´High-Efficiency Photovoltaic Devices using Trap-Controlled Quantum-Dot Ink prepared via Phase-Transfer Exchange




PbSCdS solar cell 6percent

The highly potential solar cell technology based on colloidal quantum dots (CQD), still has to overcome several problems in order to climb above the competing technologies. One of such bottlenecks is the lower than predicted open-circuit voltage due to the defects in the lattice of the QDs.

The recent work from the group of Prof. Watt (Oxford University) published in ACS’s journal Chemistry of Materials, suggests an approach to increase the voltage without a negative impact on the current. “This is done by developing a passivation strategy that uses the synergistic effect of a core/shell structure and ligands coordination to passivate CQD surfaces” tells the first author Dr. Neo.

Contrary to the sophisticated techniques of building up a solar cell, the authors decided to utilize the technology, which has an easy and cheap potential for scale-up, namely spin-coating from solutions.

Using this method, they assembled the solar cells from PEDOT:PSS, QDs and ZnO layers sandwiching them between aluminium and ITO electrodes. The core of the work was to study the influence of the QDs structure on the cell efficiency.

QD-based-laser-2013Quantum Dots Laser Developed

In a search for a more reliable and tuneable laser sources, a group of scientists led by Prof. Lee from the National Cheng Kung University of Taiwan developed a quantum-dots based laser. Colloidal quantum dots (QD) of CdSe/ZnS were embedded into a cholesteric liquid crystal matrix. The article is soon to be published in Advanced Optical Materials.

Liquid crystals, which have photonic crystal behaviour, are already used in construction of dye-doped lasers, which, however, have several drawbacks such as thermal, chemical and photo- instabilities. 

This study was the first to report a highly directional lasing emission based on a QD-embedded CLC (QDCLC) cell. Experimental results showed that the QDs had a key function not only as the nanoscaled source of fluorescence emission but also as the structural stabilizer of the CLC microresonator. 

Comparing the developed QD-laser with the existing dye-doped laser, Prof. Lee said,  "The developed QDCLC laser could tolerate a strong pumped energy without damage (over 83 μ J/pulse), and this threshold is over 1.66 times higher than that (50 μ J/pulse) of a traditional DDCLC laser. The divergence angle of the QDCLC lasing emission is 1.67 times smaller than that of the DDCLC lasing emission. Furthermore, the QDCLC laser has flexibly thermal and electrical tunabilities in the lasing threshold, linewidth, and wavelength." 

"Combining the QD gain medium and the tunable CLC resonator can potentially result in the fabrication of tunable coherent light sources or laser devices (e.g., tunable single photon laser) with advantages of low cost, highly fl exible tunability, high stability, high damage threshold, lower beam divergence, and high reusability" Prof. Lee said.

All of the materials used in this study including CdSe/ZnS quantum dots are commercially available.

Related articles:
QDs Plus MOF for enhanced Light-Harvesting
Quantum Dots Can Shine Even Brighter

NanoJam (C) 2013
Image Source: John Wiley & Sons, Inc

"Carbon nanotubes with only 10,000th the diameter of a human hair are an allotrope of carbon like graphite and diamond, and they have unique physical and electronic properties. These include a higher thermal conductivity than diamond; greater mechanical strength than steel (orders of magnitude by weight); and a larger electrical conductivity than copper. It is due to these properties that carbon nanotubes will enable electronic device manufacturers develop more innovative electronic devices. 

To help device manufacturers and the research and development community to explore the full potential of carbon nanotube based technologies, Linde is making its nanotube inks available to developers. These nanotube inks contain individual carbon nanotubes and are produced without damaging or shortening the nanotubes and therefore preserve the unique nanotube properties. This landmark development drastically improves the performance of transparent conductive thin films made from the inks and opens the door for the development of nanotube applications in not only consumer electronics, but also the healthcare sector and sensor manufacturing.

"While we've seen a lot of excitement around nanotubes in the past ten years, we've not yet seen a commercially viable nanotube solution in the market because of challenges in the processing of this great material," said Dr Sian Fogden, Market and Technology Development Manager for Linde Electronics' nanomaterials unit. "Our nanotube technology and our unique nanotube inks overcome these challenges, paving the way for completely new types of high-functionality electronic devices." 

Linde, which develops and supplies specialist materials and gases for the world's leading electronic manufacturers, is in the final development stages with its single wall carbon nanotube technology. Alongside the launch of the nanotube ink into the development community, the company will also provide its nanotube ink at large scale directly to electronic device manufacturers."

Supreme water-soluble CNTs are available for instant purchase since 2010.

Source: Nanotech-Now
Munich, Germany, Posted on June 28th, 2013

colortubesNanodiamonds for thermal fluids

Scientists of Vanderbilt University in Nashville (USA) could increase the thermal conductivity of both ethylene glycol (EG) and mineral oil by adding a small amount of nanodiamonds. Moreover, the several-fold increase compared to the predicted from Maxwell equation was experimentally evidenced. So, 12% increase of thermal conductivity in EG and 11% increase in oil could be achieved by adding 0.9% and 1.9% of nanodiamonds respectively. This finding was published recently in the ACS Nano (DOI 10.1021/nn305664x).

"Heat-transfer fluids, such as water, mineral oil, and ethylene glycol, serve important functions in many thermal transport applications but suffer from low thermal conductivity. Efficiencies of fluid thermal systems would be enhanced substantially if higher thermal conductivities of working fluids can be achieved." says Prof. Lukehart from the University's Chemical Dept. Incorporation of small solid materials of high thermal conductivity into base liquids can improve thermal conductivity of base liquids.