Carbon Dots from Human Hair Boost Solar Cells

In a study published in the Journal of Materials Chemistry A, the researchers led by Professor Hongxia Wang in collaboration with Associate Professor  Prashant Sonar  of the Queensland University of technology  (QUT) in Australia  showed the carbon nanodots could be used to improve the performance of perovskites solar cells, a relatively new photovoltaic technology, are seen as the best PV candidate to deliver low-cost, highly efficient solar electricity in coming years. They have proven to be as effective in power conversion efficiency as the current commercially available monocrystalline silicon solar cells, but the hurdles for researchers in this area is to make the technology cheaper and more stable. Unlike silicon cells, they are created with a compound that is easily manufactured, and as they are flexible they could be used in scenarios such as solar-powered clothing, backpacks that charge your devices on the go and even tents that could serve as standalone power sources.

This is the second major piece of research to come as a result of a human hair derived carbon dots as multifunctional material. Last year, Associate Professor Prashant Sonar led a research team, including Centre for Materials Science research fellow Amandeep Singh Pannu, that turned hair scraps into carbon nanodots by breaking down the hairs and then burning them at 240 degrees celsius. In that study, the researchers showed the carbon dots could be turned into flexible displays that could be used in future smart devices.

In this new study, Professor Wang’s research team, including Dr Ngoc Duy Pham,  and Mr Pannu, working with Professor Prashant Sonar’s group, used the carbon nanodots on perovskite solar cells out of curiosity. Professor Wang’s team had previously found that nanostructured carbon materials could be used to improve a cell’s performance. After adding a solution of carbon dots into the process of making the perovskites, Professor Wang’s team found the carbon dots forming a wave-like perovskite layer where the perovskite crystals are surrounded by the carbon dots.

It creates a kind of protective layer, a kind of armour,” Professor Wang said. “It protects the perovskite material from moisture or other environmental factors, which can cause damage to the materials.”

The study found that perovskite solar cells covered with the carbon dots had a higher power conversion efficiency and a greater stability than perovskite cells without the carbon dots.

Source: https://www.qut.edu.au/

How To Create a Spectrum of Natural-looking Hair Colors

We’ve long been warned of the risks of dyeing hair at home and in salons. Products used can cause allergies and skin irritation — an estimated one percent of people have an allergy to dye. Furthermore, repeated use of some dyes has been linked to cancer. But there soon may be a solution for the growing list of salons and hair color enthusiasts searching for natural alternatives to dyes and cosmetics.

Northwestern University researchers have developed a new way to create a spectrum of natural-looking hair colors, ranging from blond to black, by using enzymes to catalyze synthetic melaninMelanin is an enigmatic and ubiquitous material often found in the form of brown or black pigment. Northwestern’s Nathan Gianneschi, the research lead and associate director for the International Institute for Nanotechnology, said every type of organism produces melanin, making it a readily available and versatile material to use in the lab.

Synthetic melanin can create colors ranging from blond to black

In humans, it’s in the back of our eye to help with vision, it’s in our skin to help with protecting skin cells from UV damage,” Gianneschi said. “But birds also use it as a spectacular color display — peacock feathers are made of melanin entirely.”

Gianneschi is Professor of Chemistry in Northwestern’s Weinberg College of Arts and Sciences and a professor of materials science and engineering and biomedical engineering in Northwestern Engineering. Claudia Battistella, a postdoctoral fellow in Gianneschi’s lab, is the paper’s first author.

The research was published in the journal Chemistry of Materials.

Source: https://www.mccormick.northwestern.edu/

How To Reverse Baldness Using Nanogenerators

Few things on earth strike fear into the hearts of men more profoundly than hair loss. But reversing baldness could someday be as easy as wearing a hat, thanks to a noninvasive, low-cost hair-growth-stimulating technology developed by engineers at the University of Wisconsin–Madison (UW Madison).

I think this will be a very practical solution to hair regeneration,” says Xudong Wang, a professor of materials science and engineering at UW–Madison.

Based on devices that gather energy from a body’s day-to-day motion, the hair-growth technology stimulates the skin with gentle, low-frequency electric pulses, which coax dormant follicles to reactivate hair production. The devices don’t cause hair follicles to sprout anew in smooth skin. Instead they reactivate hair-producing structures that have gone dormant. That means they could be used as an intervention for people in the early stages of pattern baldness, but they wouldn’t bestow cascading tresses to someone who has been as bald as a billiard ball for several years.

Because the devices are powered by the movement of the wearer, they don’t require a bulky battery pack or complicated electronics. In fact, they’re so low-profile that they could be discreetly worn underneath the crown of an everyday baseball cap. Wang is a world expert in the design and creation of energy-harvesting devices. He has pioneered electric bandages that stimulate wound-healing and a weight-loss implant that uses gentle electricity to trick the stomach into feeling full.

The hair-growth technology is based on a similar premise: Small devices called nanogenerators passively gather energy from day-to-day movements and then transmit low-frequency pulses of electricity to the skin. That gentle electric stimulation causes dormant follicles to “wake up.” “Electric stimulations can help many different body functions,” says Wang. “But before our work there was no really good solution for low-profile devices that provide gentle but effective stimulations.”

Wang and colleagues published a description of the technology in the journal ACS Nano.

Source: https://news.wisc.edu/