Organic solar cells reach manufacturing milestone

William Bergius writes about an EES article in Chemistry World

In an impressive feat of engineering, scientists in Denmark have devised a rapid, scalable and industrially viable way to manufacture large sheets of flexible organic tandem solar cells. Their successful application of roll-to-roll processing is a significant achievement for this emerging renewable technology.Organic solar cells reach manufacturing milestone

An organic photovoltaic (OPV) solar cell is a polymer-based thin film solar cell. OPV solar cells have been the focus of much research as they are lightweight, flexible, inexpensive, highly tuneable and potentially disposable. They are also unparalleled in the number of times that they can pay back the energy used in their manufacture.

In the quest to improve the efficiency of OPVs, which, in addition to operational lifetime, is currently their key limitation, various new materials, processing methods and device architectures have been investigated. Among these is the tandem cell, where multiple junctions are stacked upon one another. This can increase the efficiency of the cell by not only increasing the number of junctions, but, along with careful selection of complimentary materials, can make it possible to harvest photons from a broader region of the spectrum. However, this more complicated architecture renders their manufacture significantly more challenging.

Interested to find out more? Read the full article by William Bergius in Chemistry World.

Read the original article in Energy and Environmental Science:

Scalable, ambient atmosphere roll-to-roll manufacture of encapsulated large area, flexible organic tandem solar cell modules
Energy Environ. Sci., 2014, Advance Article
DOI: 10.1039/C4EE01223B
Thomas R. Andersen, Henrik F. Dam, Markus Hösel, Martin Helgesen, Jon E. Carlé, Thue T. Larsen-Olsen, Suren A. Gevorgyan, Jens W. Andreasen, Jens Adams, Ning Li et al.

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Harvesting electricity from seawater

A new type of blue energy harvesting device may offer a practical method of continuous coastal electricity generation.

In 2011, Stanford researchers described a new form of energy harvesting device coined as a “mixing entropy battery” in Nano Letters1. Their device capitalized on the chemical energy available in a system where an ion concentration gradient is present; in this case where low salinity wastewater or river water was mixed with ~0.6 M NaCl rich seawater. It is estimated that during this mixing process, there is a free energy reduction of 2.2 kJ per liter of freshwater.

Extractable Energy Per Cycle

Extractable energy depends on charging time

Using two electrodes, one Na+ selective the other Cl- selective, a charging state exists when the battery is exposed to low salinity water, where ions in the electrodes are removed via a concentration gradient. Next, sea water replaces the low salinity water and the potential between the electrodes increases. This is followed by a discharge state where ions from the higher concentration solution reincorporate into their ion selective electrode . This charge/discharge cycle produces extractable energy per cycle as described in the figure shown.

In the present work, the same group investigates replacing the cathode material with a higher capacity material, Na4Mn9O18, as opposed to the previously reported Na2M5O10. An overall improvement was observed when researchers simulated batteries hooked up in a series, by passing the same effluent wastewater 12 times through the same cell. In doing so, the cumulative energy produced was 0.44 kWh/m3 of wastewater, compared to the theoretical maximum of 0.65 kWh/m3. This denotes an overall efficiency of 68%. Future considerations include reducing the number of batteries required in series, as well as eliminating the use of silver as a Cl- selective electrode, for environmental concerns.

1.) Nano Lett., 2011, 11, 1810–1813

Interested? Read the full advance article in Energy and Environmental Science here:

Performance of a mixing entropy battery alternately flushed with wastewater effluent and seawater for recovery of salinity-gradient energy

Meng Ye, Mauro Pasta, Xing Xie, Yi Cui, and Craig S. Criddle
Energy Environ. Sci., 2014, Advance Article
DOI: 10.1039/C4EE01034E

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The future is lead-free for perovskite solar cells

Vicki Marshall writes about an EES article in Chemistry World

A lead-free and non-toxic alternative to current perovskite solar-cell technology has been reported by researchers in the UK: tin halide perovskite solar cells. They are also cheaper to manufacture than the silicon solar cells currently dominating the market.The future is lead-free for perovskite solar cells

Nakita Noel, part of Henry Snaith’s research team at the University of Oxford, describes how perovskite materials have caused a bit of a whirlwind since they came out in 2009: ‘Everybody that’s working in the solar community is looking to beat silicon.’ Despite the high efficiency of conventional crystalline silicon solar cells (around 20%), high production and installation costs decrease their economic feasibility and widespread use.

The challenge to find a cheaper alternative led to the development of perovskite-based solar cells, as organic–inorganic metal trihalide perovskites have both abundant and cheap starting materials. However, the presence of lead in some semiconductors could create toxicology issues in the future. As Noel puts it ‘every conference you present at somebody is bound to put up their hand and ask “What about the lead – isn’t this toxic?”

Interested to find out more? Read the full article by Vicki Marshall in Chemistry World.

Read the original article in Energy & Environmental Science.

Lead-Free Organic-Inorganic Tin Halide Perovskites for Photovoltaic Applications
Nakita K. Noel, Samuel D. Stranks, Antonio Abate, Christian Wehrenfennig, Simone Guarnera, Amir Haghighirad, Aditya Sadhanala, Giles E Eperon, Sandeep K. Pathak, Michael B Johnston, annamaria petrozza, Laura Herz and Henry Snaith
Energy Environ. Sci., 2014, Accepted Manuscript
DOI: 10.1039/C4EE01076K

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Designing next-generation activated carbons for advanced energy storage applications

Activated carbons for energy storage

Activated carbons for energy storage

In this interesting and informative article, M. Sevilla and R. Mokaya review state-of-the-art synthesis methods for the preparation of activated carbons and their application in energy storage systems. Specifically, the authors detail recent developments in the control of properties such as pore size distribution, surface area and structural and chemical characteristics – and how such properties relate to performance in hydrogen storage and supercapacitors.

Activated carbons have a number of desirable features that make them attractive for use in advanced energy-storage systems. As well as being relatively light-weight, low-cost and chemically inert, they also have very large surface areas (> 1000 m2/g) and high micropore volumes in which to interact with other species. This makes activated carbons particularly useful as supercapacitor electrodes and hydrogen storage materials – where performance is strongly related to surface area and pore characteristics.

In this review, recent developments in the fabrication of activated carbons are discussed, focusing particularly on methods which allow the control of features, such as pore size distribution, surface area and physical and chemical characteristics such as texture, morphology and heteroatom-doping. The relationship between these properties and the performance of these materials as supercapacitor electrodes and their use in hydrogen storage is also looked at in detail, providing a guide for the direction of future research in this very active field.

Interested? Read the full article here:

Energy storage applications of activated carbons: supercapacitors and hydrogen storage

Marta Sevilla and Roberts Mokaya

Energy Environ. Sci., 2014, 7, 1250–1280

DOI: 10.1039/C3EE43525C

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EES Lectureship Award at Clean Energy Conference

Presentation of EES readers choice lectureship

Winner of the 2013 EES Readers Choice Award Lecture Prof. Tom Jaramillo, and EES Deputy Editor Dr Heather Montgomery

Qingdao, China was the location for the lively and informative 2nd International Conference on Clean Energy Science (ICCES2), with lectures from key figures from around the world.

Energy & Environmental Science were delighted to present Professor Tom Jaramillo with the Energy & Environmental Science Readers’ Choice Lectureship Award at the event, and Prof. Jaramillo’s talk presenting insights on how to design a sustainable and efficient catalyst for CO2 reduction was very well received.

Prof. Jaramillo was awarded the lectureship for his EES article “New insights into the electrochemical reduction of carbon dioxide on metallic copper surfaces” which was one of the most downloaded articles in 2013.

To keep up to date with the latest published articles in Energy & Environmental Science, and our news and related events, sign up to our EES e-alerts and news service: http://www.rsc.org/Publishing/Journals/forms/V5profile.asp.

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This week’s HOT articles

Take a look at this week’s selection! These articles are available free for a limited time:

Si-based Earth abundant clathrates for solar energy conversion
Yuping He, Fan Sui, Susan M. Kauzlarich and Giulia Galli
DOI: 10.1039/C4EE00256C, Communication Graphical abstract: Experimental demonstration of enhanced photon recycling in angle-restricted GaAs solar cells

Improving the photoelectrochemical activity of La5Ti2CuS5O7 for hydrogen evolution by particle transfer and doping
Jingyuan Liu, Takashi Hisatomi, Guijun Ma, Aki Iwanaga, Tsutomu Minegishi, Yosuke Moriya, Masao Katayama, Jun Kubota and Kazunari Domen
DOI: 10.1039/C4EE00091A, Communication

Performance of a mixing entropy battery alternately flushed with wastewater effluent and seawater for recovery of salinity-gradient energy
Meng Ye, Mauro Pasta, Xing Xie, Yi Cui and Craig S. Criddle
DOI: 10.1039/C4EE01034E, Paper

Experimental demonstration of enhanced photon recycling in angle-restricted GaAs solar cells
Emily D. Kosten, Brendan M. Kayes and Harry A. Atwater
DOI: 10.1039/C3EE43584A, Communication

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Poster prize winners at Israel Chemical Society Annual meeting 2014

(L-R) Prof. Ehud Keinan (President of the Israel Chemical Society), Dr. Lioz Etgar, Dr. Sabrina Sartori (Poster prize winner), Prof. Roy Shenhar (Organizing committee).

Energy and Environmental Science was delighted to sponsor the 79th Annual Meeting of the Israel Chemical Society, took place at Dan Panorama Hotel and Convention Center in Tel Aviv in February 4- 5, 2014.

The two-day symposium and exhibition, which was organised by the Hebrew University of Jerusalem, covered both basic and applied chemistry. The meeting provided outstanding opportunities for scientists and entrepreneurs, R&D researchers and engineers, students and teachers from the academy, industry and government, to interact, exchange ideas, share their new results and create new collaborative projects.

Congratulations to Dr. Sabrina Sartori, who was awarded an Energy and Environmental Science poster prize at the poster session!
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This week’s HOT articles

Take a look at this week’s selection! These articles are available free for a limited time: Graphical abstract: A wearable thermoelectric generator fabricated on a glass fabric

Improvement of open-circuit voltage and photovoltaic properties of 2D-conjugated polymers by alkylthio substitution
Chaohua Cui, Wai-Yeung Wong and Yongfang Li
DOI: 10.1039/C4EE00446A, Paper

Towards low-cost, environmentally friendly printed chalcopyrite and kesterite solar cells
Hamed Azimi, Yi Hou and Christoph J. Brabec
DOI: 10.1039/C3EE43865A, Review Article

A wearable thermoelectric generator fabricated on a glass fabric
Sun Jin Kim, Ju Hyung We and Byung Jin Cho
DOI: 10.1039/C4EE00242C, Paper

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Toilet flushes could help power homes

Abigail Hallowes writes about a HOT EES article in Chemistry World

Researchers in South Korea have devised a way to harness the motion of water, including from raindrops or from a flushing toilet, as a sustainable energy source.

Devices that renewably generate electricity in an uncomplicated manner are in demand. Now, Youn Sang Kim and his team at Seoul National University and Korea Electronics Technology Institute (KETI) have adapted a transducer to convert the mechanical energy from water motion into electrical energy.

Interested to know more? Read the full article by Abigail Hallowes on Chemistry World.

Read the original article in Energy & Environmental Science – it’s free to download until 27th May 2014!

The Effective Energy Harvesting Method from Natural Water Motion Active Transducer (WMAT)
Youn Sang Kim, Junwoo Park, YoungJun Yang, Eungkyu Lee, Soon-Hyung Kwon, Won Keun Kim, Cheouljong han, Jeongno Lee and Siyun Park
Energy Environ. Sci., 2014, Accepted Manuscript
DOI: 10.1039/C4EE00588K, Communication

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Visible light hydrogen production with carbonate-doped TiO2 microspheres

Martina Congiu is a guest web-writer for Energy and Environmental Science. Martina is currently a Research Technician in Dr Henry Snaith’s group at the University of Oxford. During her free time from work, she loves cooking and cycling in the outskirts of Oxford.

A simple “one-pot” solvothermal method has been developed to prepare high-surface-area mesoporous TiO2 microspheres in order to extend the light absorption from the ultraviolet to the visible region of the solar spectrum.

By Martina Congiu

Titanium dioxide (TiO2) is a wide bandgap semiconductor, extensively studied for photocatalysis because nontoxic, abundant, stable and photoactive. Unfortunately, bare TiO2 absorbs photons only in the ultraviolet, hence the need to find suitable dopants to enhance its absorption in the visible region.

The new nonaqueous solvothermal method carried out by Liu and co-workers, shows how it is possible to synthesize carbon-doped microspheres with high specific surface area, tunable pore diameter and grain size, high crystallinity, well-defined morphology and high visible light absorption.

Furthermore, the new material was tested as solid-state photocatalyst under visible light irradiation. The experiment showed that doped-TiO2 microspheres created with this new method have an hydrogen production rate three times higher than commercial TiO2 nanoparticles.

Interested in a better understanding about this field? Read more from the Communication:

Doping high-surface-area mesoporous TiO2 microspheres with carbonate for visible light hydrogen production
Bin Liu, Li-Min Liu, Xiu-Feng Lang, Hsin-Yi Wang, Xiong Wen (David) Lou and Eray S. Aydil
DOI: 10.1039/C4EE00472H, Communication

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