solar energy – Lightsources.org

Extending the longevity of perovskite solar cells for cheaper solar energy

2022/05/252022/05/26

Study reveals the secret to treating the ‘Achilles’ heel’ of alternatives to silicon solar panels for the photovoltaics industry

Diamond’s Nanoprobe beamline I14 and the electron Physical Science Imaging Centre (ePSIC) were used by a multidisciplinary team of researchers to gain new insight into the perovskite materials that hold so much potential in the field of optoelectronics. Focusing on structural changes that can lead to degradation, the Diamond instruments were part of a suite that enabled the group to observe the nanoscale properties of thin films of perovskite materials and how they change over time under solar illumination. The research, recently published in Nature, could significantly accelerate the development of long-lasting, commercially available perovskite photovoltaics.

Perovskite materials offer a cheaper alternative to silicon for producing solar cells and also show great potential for other optoelectronic applications, such as energy efficient LEDs and X-ray detectors.

The metal halide salts are abundant and much cheaper to process than crystalline silicon. They can be prepared in a liquid ink that is simply printed to produce a thin film of the material.

While the overall energy output of perovskite solar cells can often meet or – in the case of multi-layered, so-called ‘tandem’ devices – exceed that achievable with traditional silicon photovoltaics, the limited longevity of the devices is a key barrier to their commercial viability.

A typical silicon solar panel, like those you might see on the roof of a house, typically lasts about 20-25 years without significant performance losses.

Because perovskite devices are much cheaper to produce, they may not need to have as long a lifetime as their silicon counterparts at least to enter some markets – but to fulfil their ultimate potential in realising widespread decarbonisation, cells will need to operate for at least a decade or more. Researchers and manufacturers have yet to develop a device with similar stability to silicon cells.

Now, researchers at the Department of Chemical Engineering and Biotechnology (CEB) and Cavendish Laboratory at the University of Cambridge, together with the Okinawa Institute of Science and Technology (OIST) in Japan, have discovered that the defects that limit perovskite efficiency are also responsible for structural changes in the material that lead to degradation.

Read more on the Diamond website

Image: A typical silicon solar panel, like those you might see on the roof of a house, typically lasts about 20-25 years without significant performance losses

World changing science

2021/11/242021/11/24

Marion Flatken is a 3^rd year PhD student working in the Department Novel Materials and Interfaces for photovoltaic solar cells led by Prof. Dr. Antonio Abate, at HZB.

In her #LightSourceSelfie, Marion describes the perovskite solar cell research she is undertaking and reflects on the opportunity light sources present to scientists. She says,

“We are really having the chance to work in a unique environment and to use the knowledge and the facilities and the resources that we have to really change the world literally.”

Marion Flatken’s #LightSourceSelfie

Beamline filming location: HZB ASAXS-Instrument, FCM-beamline at PTB laboratory (Physikalisch-Technische Bundesanstalt), BESSYII

Towards catalysts for solar hydrogen production

2021/03/092021/03/10

Thin films of molybdenum and sulfur belong to a class of materials that can be considered for use as photocatalysts. Inexpensive catalysts such as these are needed to produce hydrogen as a fuel using solar energy. However, they are still not very efficient as catalysts. A new instrument at the Helmholtz-Berlin Zentrum’s BESSY II now shows how a light pulse alters the surface properties of the thin film and activates the material as a catalyst.

MoS₂ thin films of superposed alternating layers of molybdenum and sulfur atoms form a two-dimensional semiconducting surface. However, even a surprisingly low-intensity blue light pulse is enough to alter the properties of the surface and make it metallic. This has now been demonstrated by a team at BESSY II.

Read more on the HZB website

Image: A new instrument at BESSY II can be used to study molybdenum-sulfide thin films that are of interest as catalysts for solar hydrogen production. A light pulse triggers a phase transition from the semiconducting to the metallic phase and thus enhances the catalytic activity.

Credit: © Martin Künsting /HZB

Enhancing solar energy production

2019/07/102019/09/20

Research investigates ways to convert titanium dioxide into a new photoactive material in the visible light range.

The search for clean and renewable energy sources has intensified in recent years due to the increase in atmospheric concentration of greenhouse gases and the consequent increase in the average temperature of the planet. One such alternative source is the conversion of sunlight into electricity through photovoltaic panels. The efficiency in this conversion depends on the intrinsic properties of the materials used in the manufacturing of the panels, and it increases year by year with the discovery of new and better materials. As such, solar energy is expected to become one of the main sources of electric energy by the middle of this century, according to the International Energy Agency (IEA).

Titanium dioxide ( $T i O_{2}$ ) is an abundant, nontoxic, biologically inert and chemically stable material, known primarily as a white pigment used in paints, cosmetics and even toothpastes. $T i O_{2}$ is also often used in sunscreens since it is especially capable of absorbing radiation in the ultraviolet region. However, this same property severely limits the use of $T i O_{2}$ for solar energy conversion, since the ultraviolet emission comprises only 5 to 8% of the total energy of the solar light.

Can this $T i O_{2}$ property be extended to the visible light region to increase the conversion of sunlight into electricity? To answer this question, Maria Pilar de Lara-Castells et al. [1] conducted an innovative research in which they discuss how a special treatment can change the optical properties of $T i O_{2}$ .

Diamond’s 8000th publication: The future of solar cells

2019/06/272019/06/28

A collaboration between researchers in the UK and China recently led to the publication of the 8000^th research article describing cutting edge science carried out at Diamond Light Source. Professor David Lidzey from the University of Sheffield and his collaborator Professor Tao Wang from Wuhan University of Technology published their findings in Nano Energy with implications for the future of solar cells.
Fullerene molecules known as “Bucky balls” have been used as charge acceptors in solar cells for a long time. Researchers used Diamond Light Source to investigate new acceptor molecules that would be cheaper to manufacture. They discovered that depending on the molecule and the way that it was blended with polymers, they were able to see a significant efficiency increase over traditional compositions. The added efficiency came from the fact that the new compositions could absorb light over a broader wavelength range. This means that if used in solar cells, they will be able to use more of the sun’s light than is possible using current materials.
The added efficiency comes from the molecules themselves as well as the way they are blended and cast. Using the GWAXS technique at Diamond, the researchers found that flat acceptor molecules were able to stack very efficiently and that the production method allowed them to self-organise on nanometre length scales allowing aggregates to form that extend the wavelengths that can be absorbed.

Image: A representation of a “bucky ball” or fullerene molecule, commonly used as charge acceptors in solar panels.

Solar–to-hydrogen conversion

2018/02/282018/03/08

Polymeric carbon nitrides exhibit a catalytic effect in sunlight that can be used for the production of hydrogen from solar energy.

However, the efficiency of these metal-free catalysts is extremely low. A team at the Tianjin University in China, in collaboration with a group at the Helmholtz-Zentrum Berlin, has increased the catalytic efficiency of these polymeric carbon nitrides by a factor eleven through a simple process resulting in a larger surface area. The paper was published in the journal Energy & Environmental Science.

One of the major challenges of the energy transition is to supply energy even when the sun is not shining. Hydrogen production by splitting water with the help of sunlight could offer a solution. Hydrogen is a good energy storage medium and can be used in many ways. However, water does not simply split by itself. Catalysts are needed, for instance Platinum, which is rare and expensive. Research teams the world over are looking for more economical alternatives. Now a team headed by Dr. Tristan Petit from the HZB, together with colleagues led by Prof. Bin Zhang from Tianjin University, Tianjin, China, has made important progress using a well-known class of metal-free photocatalysts.

>Read more on Bessy II at HZB website

Image: PCN nanolayers under sunlight can split water.
Credit: Nannan Meng /Tianjin University

Scientists confirm speculation on the chemistry of a high-performance battery

2018/02/282018/03/05

X-ray experiments at Berkeley Lab reveal what’s at work in an unconventional electrode.

Scientists have discovered a novel chemical state of the element manganese. This chemical state, first proposed about 90 years ago, enables a high-performance, low-cost sodium-ion battery that could quickly and efficiently store and distribute energy produced by solar panels and wind turbines across the electrical grid.

This direct proof of a previously unconfirmed charge state in a manganese-containing battery component could inspire new avenues of exploration for battery innovations.

X-ray experiments at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) were key in the discovery. The study results were published Feb. 28 in the journal Nature Communications.

Scientists at Berkeley Lab and New York University participated in the study, which was led by researchers at Natron Energy, formerly Alveo Energy, a Santa Clara, California-based battery technology company.

The battery that Natron Energy supplied for the study features an unconventional design for an anode, which is one of its two electrodes. Compared with the relatively mature designs of anodes used in lithium-ion batteries, anodes for sodium-ion batteries remain an active focus of R&D.

Photo: An array of solar panels and windmills.
Credit: PxHere

Fuel from the sun: insight into electrode performance

2018/01/232018/02/02

Soft x-ray studies of hematite electrodes—potentially key components in producing fuel from sunlight—revealed the material’s electronic band positions under realistic operating conditions.

In photosynthesis, plants use sunlight to split water into oxygen and hydrogen. The oxygen is released into the atmosphere, and the hydrogen is used to produce molecules—such as carbohydrates and sugars—that store energy in chemical bonds. Such compounds constitute the original feedstocks for subsequent forms of fuel consumed by society.

Photoelectrochemical (PEC) water splitting is a form of “artificial” photosynthesis that uses semiconductor material, rather than organic plant material, to facilitate water splitting. Electrodes made of semiconductor material are immersed in an electrolyte, with sunlight driving the water-splitting process. The performance of such PEC devices is largely determined at the interface between the photoanode (the electrode at which light gets absorbed) and the electrolyte.

>Read more on the ALS webpage

Photo: Roy Kaltschmidt