Thermoelectric materials are semiconductors that can generate a temperature change when an electrical bias is applied across them (or vice versa!). Semiconductor materials are of two types: n-type, or materials that have a higher amount of negatively charged electrons, and p-type, or materials that have a higher amount of positively charged holes. How thermoelectric materials work in cooling systems is through a semiconductor device called a Peltier element, also known as a Peltier couple.

Here, an n-type and p-type semiconductor are connected in an electrical circuit such that when an electric voltage is applied, the electrons in the n-type semiconductor and the holes in the p-type semiconductor travel in the same direction, carrying with them heat!

Picture credit: www.peltier-info.com

This is a reversible phenomenon that causes electronic charges to travel from one side to another, carrying heat with them from a hot side to a cool side, thereby cooling the hot side. Typically, the efficiency of standard thermoelectric devices is not super high, and they can be hard to use in applications like air conditioning or refrigeration. Instead, they’re more commonly used in niche scenarios where compactness, precision, and solid-state reliability matter more than efficiency, like cooling laser diodes, infrared sensors, portable beverage coolers, or CPU chips. You’ll find them in spacecraft instrumentation, lab equipment, and high-end electronics — basically, places where moving parts are a liability or miniaturization is non-negotiable.

Researchers at Johns Hopkins University recently published an article on creating new thin film thermoelectric semiconductor materials that can be used for solid-state cooling in refrigerators! Read about their work here — https://bit.ly/jhu-thermoelectrics. In their work, they fabricate thin nanostructures called CHESS —controlled hierarchically engineered superlattice structures. They use alternating stacks of materials called Bismuth Telluride and Antimony Telluride, grown by a technique called metal organic chemical vapor deposition (MOCVD). This technique can be used to deposit extremely thin layers of materials, up to a single layer of atoms thick!

Using this method, they show that they are able to use a module of 16 P-N Peltier couples to deliver usable cooling at a 5W scale. Therefore, they claim that by using their nano-engineered CHESS materials, they can achieve both high capacity and high-performance thermoelectric cooling, pushing solid-state refrigeration closer to practical, real-world use. The idea that these materials aren’t just useful at the lab scale, but also can be used practically for large volume cooling is pretty “cool”. While it may be an early demonstration, they’re positioning it as a meaningful step toward real, scalable, solid-state refrigeration.

They also talk about how their high-efficiency thermoelectric cooling modules, being used for large volume cooling applications, could reduce our dependence on larger, bulky cooling systems, specifically the current mechanical systems that also contribute negatively to the environment by using chemical coolants containing hydrofluorocarbons (HFCs) and worsen greenhouse gas emissions. As the temperatures rise due to climate change, there is a need for more efficient cooling systems that don’t worsen the problem. Technology like this could also be a step in that direction.

While these interests are diverse, they stem from a source of passion, and I truly want to pursue each one of them, something I bet many of you can relate to. And like several of you, I have also grown the quintessential guilt in me, which comes with an ever growing list of unticked projects on the list. The excuses for not following through on these projects also seem to grow proportionally.

If you can relate to this dilemma, here are few tips, nay, rays of hope, that can help us passionate souls get started, and delve deeper into our creative pursuits while enjoying it. Let’s get started:

1. Set attainable goals:

We have heard this so many times: we vastly overestimate how much we can accomplish in a day, and underestimate how much we can accomplish over a period of time. Starting to learn the ukulele does not mean one needs to start learning to play songs right away! Set small, realistic and achievable goals based on the time you have on hand to consistently work on your project.

For Day 1, just learning how to tune your ukulele can be a wonderful starting point! And remember, committing to maybe just half an hour a week, or ten minutes a day is nothing to laugh at, especially when you look back a month or two from when you started!

2. Set monthly/ weekly goals:

Setting short term (realistic) goals in the direction of projects can really help! This can act as a great motivation to consistently work on the project. Looking at it as a challenge can help you get started, and keep at the task, because you have a completed project to look forward to. If those goals seem too overwhelming or challenging for you, try to break them down into weekly goals, or even reduce the size of your goal depending on how much time you can truly commit to the task!

3. Join a challenge!

One of the best ways to set a monthly goal and set some good accountability is to either start, or join a monthly challenge with a group of friends. When you have some company working towards your goals, it can feel a lot easier! Paper and Cardboard automatas are something I am passionate about, and so I joined a paper engineering 30 day challenge by Paper Crane Lab to help me create ten automatas in 30 days. Not only do I have accountability, I also get to see the work of other peers working towards similar goals, which can motivate and push me further. If paper engineering is a long ignored passion project of yours, take the first step right now, by committing to the challenge by DM-ing Paper Crane Lab!

4. Allow time for mistakes and experiments:

While being goal oriented is all fun and great, we have to remember that this is a project we are passionate about. So it is imperative we feel excited and learn throughout the process. Embrace the mistakes and try to experiment different techniques along the way. Say you started working on creative code. Sometimes, there can be errors in the code that can stop the program, or, turn a piece of code into an unintended piece of art. Learning about the techniques, and trying out things at your own pace can be an enjoyable way to improve your skills.

5. Don’t be afraid to ask for help:

Starting a journey can be overwhelming by itself, because we still need time to figure out how to begin. A really great way to drastically break through the overwhelm is to simply ask people for help. One of my long term goals was to perfect the splits, and no matter how many stretches I followed from Youtube, I was just not able to work through it, which led to demotivation. I signed up for body conditioning classes, and I can truly feel my body respond to the stretches, and I can see that I am closer towards achieving my goal!

In summary, pursuit of passion projects can rarely be straightforward. We have got to remember that at the end of the day, these are projects we truly want to work on, because they are things that mean a lot to us. Small steps in the direction, over a period of time can add up, and give us the satisfaction in the pursuits we desire. Here’s to crossing off pursuits from our list to make room for new ones!

Quantum dots are revolutionizing the field of nanotechnology, offering exciting possibilities in everything from displays to medical imaging and solar cells. These tiny semiconductor particles, typically only a few nanometers in size, exhibit unique optical and electronic properties due to quantum confinement effects. How can they be made from kitchen waste?

Essentially, when the size of a material shrinks down to the nanoscale, the behavior of electrons changes significantly, leading to tunable light absorption and emission properties. This ability to fine-tune energy levels makes quantum dots highly attractive for applications in high-efficiency photovoltaics, bio-imaging, and next-generation displays.

High performance quantum dots are often made from toxic heavy metals such as cadmium selenide or lead sulfide, posing environmental and health concerns. Enter carbon quantum dots (CQDs): a class of quantum dots synthesized from carbon-rich materials, offering a non-toxic and environmentally friendly alternative. What makes CQDs particularly exciting is that they can be literally made from biological waste, including fruit peels, leaves, and other organic matter!

How? Researchers from across India and Korea have recently demonstrated an innovative way to extract CQDs from an unlikely source — kiwi fruit peels. Kiwi, well known for its rich vitamin C content and antioxidant properties, also contains a high concentration of carbon-based compounds. Scientists have leveraged this abundance of organic material to create CQDs using a straightforward, low-cost process known as hydrothermal synthesis. In this method, kiwi fruit peels were crushed with water in a standard commercial mixer grinder. This was then mixed with a little ammonia and heated in a autoclave for 24h at a high temperature of 200 C. Once this mixture cooled, the carbon capped quantum dots floated up in the supernatant of the mixture, which was then filtered and collected. These carbon quantum dots– the same class of nanoparticles found in your expensive QLED TVs were literally made using a standard mixer grinder found in Indian kitchens! Read their research here!

What makes kiwi-derived CQDs even more compelling is their potential in the field of photovoltaics. Solar cells rely on materials that efficiently absorb sunlight and convert it into electricity. The tunable energy bandgap of quantum dots enables greater control over light absorption, potentially improving the efficiency of solar cells. By incorporating kiwi CQDs into photovoltaic devices, researchers aim to develop low-cost, high-performance solar panels that not only improve energy conversion rates but also utilize waste materials in the manufacturing process. The potential to create scalable, eco-friendly solar technologies could significantly lower the environmental impact of solar energy production.

Beyond photovoltaics, kiwi-derived CQDs have shown promising applications in bioimaging, optoelectronics, and environmental sensors. Due to their fluorescence properties, they can be used as bio-labels for tracking cellular interactions, offering a safer alternative to traditional fluorescent dyes. From harvesting solar energy to advancing cancer research, CQDs have the potential to make a remarkable impact across multiple industries. Clearly, big things indeed come in small nano-sized packets!

As research into carbon quantum dots continues, the development of sustainable, waste-derived nanomaterials is gaining momentum. Fruit peels, often discarded as waste, are proving to be a valuable resource in the quest for cleaner, greener technologies. By harnessing the power of nanotechnology and sustainability, scientists are paving the way for a future where waste is not just reduced but repurposed into high-performance materials that can be used across various industries. The journey of quantum dots — from theoretical curiosities to real-world game changers — is unfolding, one fruit peel at a time.

Imagine futuristic movies and tv shows that have sophisticated sensors and smart devices all around people’s homes — automatic kitchen gizmos, robot housekeeping and those incredibly fancy window panes that can turn into giant displays! The windows fascinated me the most, and I was probably the most excited to learn about solar-powered windows, given the steep environmental cost of powering these “futuristic gadgets”. Solar windows are essentially semiconductor devices that act as a transparent window to the world outside from the inside while protecting your privacy and generating electricity. Their features even potentially allow them to act as displays — making my ten year old Futurama-watching self’s dreams come true! Although realistically for now, the primary objective of these devices is to reduce indoor heating and those astronomically rising energy bills.

Solar cells as rooftop solar panels — can we imagine a different future?

How do they work? “Solar glass” was developed by researchers at Michigan State University in 2014. Solar cells work by absorbing solar energy in very specific wavelength ranges depending on the active semiconductor material inside it. When the absorbed energy is equal to a specific energy called the bandgap energy of the active material, it generates something called an exciton — which is an excited electron (negative charged particle) and hole (positive charged particle) pair. These charges travel through the metal contacts on either side of the active material to generate electric current as you can see in the picture below.

By studying sunlight that earth receives, scientists have discovered that capturing light in the near infrared/infrared regions of the electromagnetic energy spectrum contributes to the highest efficiency of light conversion into electricity (which is why materials like Gallium Arsenide and Silicon work so well! ). However, these materials also absorb visible light which doesn’t allow them to be “transparent”. Active materials that are “transparent” have poor efficiency because of the amount of solar (photon) energy in these wavelength ranges. So the MSU researchers found a way to overcome this by using something called solar concentrators. These are clever glass designs that trap sunlight and concentrate it over a solar cell device. As the device is exposed to much more photon energy per unit area than their average rooftop solar panels counterparts, these devices make up for their shortcomings and show higher overall efficiencies!

This technology is currently being explored to make solar cells that can be transparent, flexible, and have higher efficiencies to be used in the real world! The potential applications range from house/rooftop coatings to even films on vehicles and windows. Here’s to exciting prospects of novel ways to generate renewable energy — one window pane at a time.

Sources: https://msutoday.msu.edu/news/2014/solar-energy-that-doesnt-block-the-view

Figure 1: Toast, Tiffany’s, and Transistors. Source: Photos by Mishaal Zahed, Tommao Wang and Alexandre Debiève on Unsplash (free to use via Unsplash)

What binds the three (seemingly unrelated) words in the title together? If you don’t already have a hunch, perhaps a read through this article will help answer that question. But first, let us talk about earth, and life on the blue planet. All life on earth is carbon-based, which means that it is made up of naturally synthesized “organic compounds”. These are essentially long chains of primarily carbon and hydrogen, and other elements such as oxygen, metals, and halogens. Carbon is the fourth most abundant element in the known universe and is present in virtually every molecule in the bodies of all organisms and life functions. It is not a stretch to say that carbon and carbon-based compounds play a fundamental role in our existence!

Apart from constituting the building blocks of lifeforms on earth, carbon is found both in its elemental state, and as molecules to form gases in the atmosphere, minerals in rocks and sediments in the oceans. One would expect to see less “diversity” in the appearance of elemental carbon; however, it exists in several forms! It turns out that elements can exist in different physical forms with varying properties owing to the structure of the atoms that form them -some may have specific patterns and periods. Different forms of the same element are called allotropes. Let us walk through some of the commonly observed allotropes of carbon.

Imagine a scenario where we wake up in the morning and pop some bread in the toaster and forget to turn it off. The smell of burnt toast is probably the first thing that comes to our mind when we think of “carbon”: a charred, black, smoky mass. This is essentially an amorphous form of the element, which means that the carbon atoms in this form are disordered with no periodic arrangement. Other examples of amorphous carbon include coal, charcoal and even soot and ash that remains after an incomplete combustion. The structure of amorphous carbon has been illustrated in Figure 2.

Figure 2: Molecular structure of amorphous carbon. Source: Image by Michael Ströck (mstroeck) uploaded to wikimedia.commons.org (licensed under CC).

When carbon atoms are arranged in a periodic pattern, it forms crystalline allotropes, mainly, diamond and graphite. Diamond is the hardest known substance on the planet. How is it possible for the same carbon that scrapes off the side of a piece of toast to exist as a sparkly hard piece of rock? The structure of diamond involves repeated patterns of a single structure as shown in Figure 3. Here, one carbon atom is attached to four other equidistant atoms by strong chemical bonds called covalent bonds to form a tetrahedral structure. Covalent bonds are formed when an electron pair between two atoms are shared such that the energy of the bound molecule is lower than that of the individual atoms. When this elemental block of a diamond crystal repeats itself many, many, billions of times throughout the material, it becomes stable (due to the lower energy) and hard.

However, glittery jewels at a Tiffany’s are far from how diamonds are found in nature. Natural diamonds are formed hundreds of miles under the earth’s surface due to high temperature and pressure. They can take up to millions of years to take shape. These raw diamonds are first mined, then processed to cut along tetrahedral planes of the crystal and polished to reflect light across the cut planes. This process enables diamonds to “sparkle”, which can enthrall hearts (and wallets)!

The other crystalline form of carbon is graphite, otherwise known as the smudgy silver-gray residue on our hands after a long day of pencil work. This structure of carbon involves two-dimensional sheets of hexagonal “grids” formed where carbon is present at every vertex of the sheet, as shown in Figure 3. While each carbon atom within a sheet is attached to another by covalent forces, the two-dimensional sheets themselves are loosely attached to each other by weak physical forces. These intermolecular forces are called van der Waal’s forces. Due to these weak forces between the 2D layers, graphite as a material is soft and slippery, extending application as lubricants.

A single two-dimensional layer of graphite is called graphene, which is the earliest 2D material discovered! This material gained prominence after its isolation by Andre Geim and Konstantin Novoselov (for which they received a Nobel Prize in 2010!). Due to its high conductivity and semi metallic nature, graphene has interesting electronic, material, and optical properties that make it suitable for extremely small (and ultra-fast!) transistor and nanoelectronics applications. The discovery of graphene has also led to the synthesis of several 2D materials which have allowed for sub-5 nm transistor technologies to come to life. To imagine how small this is, roughly 15,000 such transistor devices can be lined up along the diameter of a hair strand!

Figure 3: Molecular structure of allotropes of carbon showcasing both amorphous and crystalline forms including graphite, diamond, fullerenes and carbon nanotube (CNT) as labelled. Source: DOI:10.1016/j.enconman.2018.04.073 (licensed by CCC)

From toast, to Tiffany’s, to transistors, the simple carbon atom has demonstrated a wide range of structures, properties, and applications. The variations of its allotropes depend on periodicity of the atomic arrangements (amorphous or crystalline), the crystal structure, and bonds (tetrahedral covalent bonds and 2D hexagonal sheets connected by weak molecular forces). Further understanding of these atomic structures and their implications on material, optical and electronic properties will help unravel more information about carbon and carbon-based materials. This in turn will allow for potential discovery and synthesis of several other materials, leading to tremendous growth especially in the fields of electronics, communications, medicine, and energy.

Take a look at that image for a second.

Now imagine one more person coming up to that car and trying to sit on it. In my mind, the car would flatten out like a Tom and Jerry comic sequence and probably blow up.

My mind is truly truly Indian. Why? Have you heard of this popular joke going around that says India is a country where 6 people sit on a train seat meant for 3 people, and a 7th person comes along and says, “Swalpa adjust maadi” and squeezes in between them? My mind is currently like that train seat, home to a large number of ideas, goals and ventures. Every now and then, a brilliant world-changing idea crops up, something that my mind is far too excited to let go off, and begs to occupy it. As someone with an incredibly weak will, I willingly accommodate.

Now, accommodation of ideas and goals is quite different from actually fulfilling any of them. Let’s go back to that picture of the car. My mind, the car, wants to operate beautifully, flawlessly, as if it were seating bare minimum capacity in it, and reach the destination in the most perfect way possible. The problem comes when there are multiple passengers with multiple destinations and journeys of different time durations. Added to the fact that there are far too many passengers than the car can actually hold, the poor car is physically traumatized to handle all the aspirations of the engine. It might falter, it might keep stopping on the way. It might take a long time to start and it might just break down, it might just crash, just freeze and refuse to move an inch off the spot.

I’m lucky my mind is a little bit stronger than that.

Only just a little bit. It hasn’t broken down yet.

My mind comes up with brilliant ways of screwing itself over. When I am neck deep in some long overdue procrastinated commitment, it suddenly manages to come up with a new tune, or a new theme, or an exceptionally creative idea that I would love to immerse myself in. It takes me all the strength that I have to steer myself away from reading and thinking about how to achieve that idea, roughly half a day later. The net result? I have not completed what I had to finish, and I have attempted guiltily and half assed-ly at this beautiful idea that I feel miserable about not giving my full attention to.

This, I realized was probably why I was so deep into that pool of self hate that I have written about before. I am neither completing tasks that I need to finish in order to feel secure about myself, nor am I allowing myself freedom to attempt at that exciting and creative, though risky venture that my soul craves for in order to survive. I most definitely am a mind of creativity and passion. I NEED to be constantly fueled and motivated by my own mind, my own ideas and my own thoughts, which when suppressed for too long, make me extremely unhappy.

I had told myself that this year, I would start trying to fix whatever I believed was wrong with me, and build whatever part of myself that I had been building, on my way to becoming a person that I would be happy to be. So this revelation, although greeted by my mind as a travesty, was forced by my conscious will to be treated as a challenge in my life, a fun puzzle that I would try to solve for myself.

What was I writing about again?

Yes, the car. My mind.

I have a problem at hand. I want to do lots and lots of things. And I want to do them all very very well. There is neither space in my mind, nor the time in my hand to be able to do it all.

What can I do about this?

I build a car station. With a nice roof, nice comfortable seats and plenty of space for the ideas to move around. I make multiple trips with just enough ideas in the car for it to function as smoothly as I am okay with, and I make the journey with just these ideas travelling with me. At peace, because I know I will come back for the rest of them, and they will have their turn too, very soon.

I am a sucker for beautiful stationery. I have gone to places from where people return with beautiful pieces of memorabilia and I return with a fancy notebook, flamboyant pens and maybe a stack of post its (because they looked so pretty!). I might as well put that all to use!

I am going to keep a dream journal. This is where I will document all those creative ideas and goals that flash to my mind, and I will write up a rough date when a particular idea or goal will travel with me. Whenever any thought or idea related to it pops up in my mind at any point of time, I am going to go back and write it down in the journal, so I am confident of returning to that train of thought whenever I get back to it at that later date.

Unfortunately, I am no Hermione Granger to be lucky enough to have got a time turner to be able to get all the trips done simultaneously. Although I really wish I could. Hey! What if I could write a story about… (this one goes into the dream journal, for future reference and brainstorming). I am going to consider flexible lengths of journey, maybe a week, maybe a month, maybe even a year, for different passengers, and bring aboard replacements after successfully dropping them off at their destinations.

I am at peace, because the car station is really quite beautiful, and the ideas are all quite well preserved. I will keep transition times where the ideas can come and check my car out when it isn’t traveling in complete focus. It seems like a pretty good way to get all the passengers home, and feel a lot better about myself.

Of course, this will require a lot of patience. A LOT of patience. The Capital letters don’t even convey half as much as I need it. I will need to be patience with myself, with my situations and the journey. This is no ideal path, and I know I will have many unpleasant journeys on the way, but any thoughts inducing self hate seeking a ride along the road should be gently avoided, and ignored.

Now what I must do, is try figuring out how many passengers my car can fit, and place the rest of my passengers in the car station. Don’t you worry, dear brilliant idea, I will come back for you very very soon. For ideas may go, and ideas may come, but the car moves on forever.

Hang on, as soon as I figure out how to run this thing.