Researchers at the University of Toronto for the facu l ty o f Appl ied Sc ience & Engineering have recently cleared a manufacturing hurdle in the development of Perovskite solar cells. Researchers be l ieve that th is a l ternat ive so lar technology could be printable as well as being low cost.

Background

A Perovskite solar cell is relatively new and does not need to be processed to a high purity like silicon solar cells. They also require less energy and no hazardous solvents. Perovskite solar cells require a layer of tiny crystals (1/100th the width of a human hair) made of low-cost light-sensitive materials. This enables these raw materials to be mixed into a liquid forming a ‘solar ink’, which in turn can be printed onto glass, plastic, and other materials. This can be done using a rather simple inkjet process found in some printers.

But it’s not that simple…!

For the solar cell to work, electrons excited by solar energy have to be extracted from the crystals so a current can flow. This happens in an electron selective layer (ESL), but manufacturing a good ESL at low temperatures is hard. Effective ESLs have to be baked at a temperature above 500˚C, which would melt the plastic or silicon cell. However, researchers have now developed a chemical reaction that takes place under 150˚C and allows for the growth of an ESL

nanoparticle solution on top of the electrode. The new nanoparticles are coated with a layer of chlorine atoms, which help bind the Perovskite layer to the electrode. This allows for more efficient extract ion of electrons. Following this process, solar cells with an efficiency of 20.1% were created, which for the low-temperature process was the best ever reported. In fact, the cells can retain more than 90% of the efficiency even after 500 hours of use!

The future

This process can give rise to a range of applications, from charging cases for smartphones to solar-active tinted windows. But in the short term, it could be used with conventional solar cells. The researchers believe that with the low-temperature process, Perovskite solar cells could be coated directly on top of silicon. This could improve the efficiency by 30%, making it a more economical process. Should this technology be used in the right way, it could potentially lead to more uses and an improvement in consumer solar cells, as more electrical energy will be produced.

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Contributors

Theo Brownlie Ellie Carrow

Tom Hall Lincoln Heng

Ben James Reuben Lindsay-Smith

Anson Ng Dan Potter

Louis Stanbury Henry Vijayaratnam

Editor

Harry Cooper-Simpson

Staff supervisor

Miss Hayashi

If you are interested in writing for the Periodical, please get in contact with

Miss Hayashi or Harry Cooper-Simpson.

Issue 01 | March 2017 King’s College pupils explore the limitless world of chemistry…

Printable Polar Solar Cells Tom Hall (Lower 6th) investigates the latest in Perovskite solar cells

P15

I53

Er68

O8

D123

I53

C6

Al13

A Washington State University team h a s r e c e n t l y d i s c o v e r e d a n improvement in a commonly used catalyst in the oil industry. This could save energy and reduce pollution by a huge margin.

How does it work?

Methane is a by-product in a lot of industrial processes and it is a potent greenhouse gas. It also acts as the most used gas to heat homes and can be converted into electricity. It does not break apart very easily so a nickel-based catalyst is used. This converts the methane into energy, although it is often cheaper to just burn the methane, resulting in huge amounts of greenhouse gases being

released. It also wastes energy, and this is bad as in the US, methane is reported to make up to 25% of the country’s natural gas consumption.

A nickel-based catalyst

Recently, researchers have improved a catalyst so that it uses a lot less energy. They claim to have achieved this by adding a very small amount of carbon to the catalyst, which creates nickel-carbide. The catalyst allows for bonds t o b e b r o k e n a t m u c h l o w e r temperatures. The amount of carbon has to be extremely small as too much carbon in the catalyst would kill the reaction, but a low concentration will improve it.

At Bristol University, the whole chemistry lab had to be evacuated due to a student producing an explosive called TATP, the same chemical used in the Paris attacks in November 2015.

The production of TATP, also known as triacetone triperoxide, prompted the fire service and bomb disposal experts to be called to the building and a controlled explosion was carried out.

When TATP was produced, the student in question was following instructions in a published method. The chemical was an unfortunate by-product and was identified during the risk assessment process.

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Bomb Scare at Bristol University Lincoln Heng (4th Form) reports on the explosive chemical, TATP

Catalysts Reducing Pollution Ben James (4th Form) on how carbon can be used to reduce waste

Did you

Four new elements have been named?

Reuben Lindsay-Smith on how the IUPAC (International Union of Pure and Applied Chemistry) named the newest elements.

113: Nihonium (Nh)

115: Moscovium (Mc)

117: Tennessine (Ts)

118: Oganesson (Og)

Why the different endings? The names of all new elements should have endings that reflect and maintain historical cons is tency. Th is would be ‘-ium’ for elements belonging to groups 1-16, ‘-ine’ for elements of group 17 and ‘-on’ for elements of group 18.

What about other languages? It is crucial that the names for elements translate properly into all major languages. That’s why new names are often related to places or people.

Can you work out the places that elements

113, 115 and 117 were named

after?

know…

Picture a cheeky, hot summer’s day. Which of the following sounds ideal to you: lying on a beach in the bright sunshine, drinking an iced tea on a yacht trip, or watching the television with the air-conditioning on?

Three-quarters of all US-families have air-conditioners, which use about 6% of the US-produced electricity annually. Air-conditioners work in a similar way to refrigerators: they both use energy and refrigerants to transfer the heat from the interior to the outside. There is a cooling coil built inside refrigerators and air-conditioners, as well as an external hot coil, located outside the building. A refrigerant is used to absorb any heat from the air coming inside, allowing it to cool down and be delivered as cold air to the house.

However, the refrigerants currently used are chlorofluorocarbons. These are considered to be detrimental to the ozone layer of the atmosphere and therefore our environment due to the free radicals formed. The gases produced each year from the usage of air-conditioners have a longer-lasting destructive effect on the general wellbeing of organisms as well.

Providentially, Mitsui Chemicals has invented polymethylpentene, or TPX, which may be our way out in the future. It is a thermoplastic polymer of 4-methyl-1-pentene, which can be transformed into a commercially available, transparent substance for cooling purposes. When the roof of a building is covered with this material, it reflects the radiation from the sun back to space, keeping the temperature of the building underneath cool.

Polymethlypentene prevents heat from getting into the building, but also transfers heat from the building to the atmosphere, cooling it in the process. The scientists also added glass beads to the material, which can effectively alter the wavelength of the radiation that is trapped.

However, this technology has one problem: the regulation of heat removal. A simple solution to this could be to use water pipes as a medium to carry heat. By regulating the flow rate of the water, the amount of heat to be removed can be controlled, therefore maintaining a nice and cosy temperature without using too much power.

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Air-Conditioning: A Thing of the Past? Anson Ng (Lower 6th) explains how you can be sustainable while keeping cool

Did you

Hydrogen is an excellent fuel?

Henry Vijayaratnam reports on scientists at Lawrence Livermore National Laboratory, who have created an eff ic ient hydrogen storage system that could revolutionise hydrogen-powered cars.

Trouble with storage

Hydrogen has proved to be a challenge to store. This is because it is very hard to find a material that is lightweight, solid-state, and can also be used for low pressure storage.

The solution

The team has managed to develop a storage system by putting other materials like carbon into the metal hydride. This can increase the r a t e o f d i f f u s i o n , meaning that hydrogen can escape faster.

know…

A study has proven that the high l e v e l s o f b r o m i n a t e d fl a m e retardants (BFRs) found in cats come from our homes!

What are BFRs?

These are chemicals that are added to textiles, furnitures and electronic equipment to prevent them from igniting. Cats become exposed to the chemicals in the form of dust.

What are the health problems?

BFRs can lead to hyperthyroidism, as shown by a study in which blood samples of di fferent cats were compared. Indoor cats, who spent more t ime in homes and were therefore more susceptible to BFRs, were found to have more health-related problems than their outdoors counterparts.

Is it just cats that are affected?

BFRs can also affect humans! In fact, small children are particularly at risk of thyroid problems because they put things in their mouth all the time!

In Malawian homes, smoke is eye-stingingly visible and blackens walls. But it is the invisible effect it has on the lungs that makes it so deadly.

Indoor air pollution

The WHO estimates that four million premature deaths every year is due to indoor air pollution. In 2010, the UN launched an organisation called the Global Alliance for Clean Cookstoves (GACC), and they aim to get clean stoves and fuels to a million households by 2020.

A study run in Malawi over the last two years has tested whether cook stoves are better for the health. They gave a cook stove to half of the families in the study, while the

control group continued to cook over an open fire. The health of children in both groups was tested regularly.

The bad news

The results were very disappointing for the alliance as it showed there was no difference between the children with a safe stove and an open one.

The good news

Even if it did not reduce pneumonia, families with the new stoves claimed that their chronic coughs improved and that members with asthma suffered fewer attacks. Village leaders also said that nearby vegetation grew better in areas that had made the switch to the cleaner stoves.

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Toxic Chemicals Found in Indoor Cats Ellie Carrow (4th Form) on the chemicals that are putting cats at risk of diseases

Did you

CO2 can be converted to

methane fuel?

Dan Potter and Louis Stanbury (4th Form) look into a new way of creating fuel.

Using UV light and rhodium nanoparticles, researchers at Duke University have found a way of turning CO2 into methane fuel.

Rhodium is one of the rarest elements on Earth, but it plays an important role in our lives. Small amounts of the metal are used to speed up a number of industrial processes, including the making of drugs, detergents, and fertilisers. They even play a major role in breaking down toxic pollutants in our cars.

Having found this catalyst , the team hope to develop this so that it will work using only natural sunlight.

know…

Smoke Free Stoves Against Pneumonia? Theo Brownlie (4th Form) explains a possible way to stop deaths from pneumonia