Centre for Sustainable Chemical Technologies

Scientists and engineers working together for a sustainable future

Tagged: Solar cells

Hybrid Organic Photovoltaics Conference, Swansea, 2016

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📥  Comment, Seminars & Conferences

This post was contributed by Oli Weber following his attendance at the Hybrid Organic Photovoltaics Conference (28 June - 1 July 2016).


Recently Dom Ferdani (cohort ’14) and I took a trip to the south coast of Wales to attend the 2016 Hybrid Organic Photovoltaics Conference (HOPV 16). The venue was Swansea’s brand new Bay Campus, a huge new development of university buildings sited right by the beach of Swansea Bay. On the first conference day we were met by serious weather blowing in from the sea, leaving delegates from warmer climes wondering what manner of people could be mad enough to inhabit such a cold, damp land. Bay Campus is also the new home to SPECIFIC, the conference hosts, whose mandate is to span the space between academia and industry to develop materials that turn buildings into power stations using functional coatings. Building integrated photovoltaics (BIPVs) are one of the families of technologies developed at SPECIFIC. These rely on thin, lightweight, flexible designs and manufacturing methods, such as printing, that scale up well. Organic semiconductors, dye sensitised solar cells, CIGS and CZTS are all under research and development, however the technology that has come to dominate the research focus for this conference is hybrid perovskite solar cells.

Dom and Oli in Swansea

Dom and Oli in Swansea

Hybrid perovskites combine the properties of some of the highest quality known semiconductors, such as GaAs, with the solution processability of organic materials. This means that the solar cells could be manufactured at low cost, while still displaying the high efficiency of the best inorganic thin films. Unfortunately the hybrid perovskites are not very chemically stable and are easily attacked and degraded by water. Some of the typical device layers used in perovskite cells may also be contributing to the degradation, so it is still difficult to assess whether these materials will be intrinsically stable, over a 25 year lifetime, if they are properly encapsulated as protection from the environment. It was encouraging to see stability data discussed during the research presentations, particularly in the talk by Professor Mike McGehee of Stanford, whose group is developing semi-transparent perovskite top cells to include directly above standard silicon modules to make a more efficient tandem stack.

Other highlights for me personally were the advanced printing techniques run by SPECIFIC researchers on the day before the conference commenced, when we learnt about the pitfalls that await between laboratory scale work and development of cells suitable for bulk manufacturing at large scale. Professor Laura Herz of Oxford Physics gave an excellent presentation on the amount that can be learnt about charge carrier dynamics within perovskite semiconductors using terahertz photoconductivity and photoluminescence measurements. From the University of Bath, Professor Aron Walsh and Dr Petra Cameron both presented recent research results.

Overshadowing the whole conference was the spectre of Brexit. Many people had learnt the referendum result just before setting out to Swansea. Swansea is one of the areas of the UK that voted to leave despite receiving extensive regeneration funding from the EU; SPECIFIC itself is part EU funded. The research groups present were drawn from diverse international backgrounds and many of the research collaborations, already in progress or spawned during the conference, span the EU and further afield. One thing for certain is that the scientific community will continue to find ways to maintain their international networks and friendships whatever the political landscape. From my point of view (and that of many I spoke to) it’s frankly embarrassing that the referendum campaign was fought, won and lost on the basis of fear, lies and bigotry, drowning out all vestiges of the rational debate scientists thrive on. For a country priding itself on freedom and enterprise, we cannot claim to have a healthy political or media culture.

Sitting on the terrace of the conference hall, the beach ahead of me, it is impossible to ignore the juxtaposition of frenetic scientific activity behind me, as brilliant people from every part of the world work to develop clean energy sources for the future, with the EU and Welsh flags taut in the sea breeze just in front and, visible further along the coast, Port Talbot steelworks, in the news as 4,000 people wait on tenterhooks to hear if their livelihoods will disappear. Swansea is an area already hard hit by disappearing traditional industries, on the sharp end of globalised trade. The referendum vote has already delayed and could wreck buyout bids to retain the steelworks, with 69% of Welsh steel exported to the EU. Projects like SPECIFIC serve a dual purpose, for research and as attempts to sow new seeds of industrial activity for clean technologies for the twenty first century. If and when the UK regains political leadership, it will be up to UK government to prove it can support these activities as well as the EU did, or risk watching top researchers and research, as on display at HOPV, move elsewhere.


Oli is Cohort '13 of the CSCT, studying towards his PhD on "Optimizing energy harvesting processes in metal halide photovoltaics" with Professor Mark Weller and Professor Chris Bowen.

 

6th European Kesterite Workshop

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📥  Seminars & Conferences

This post is contributed by Mako Ng.

A trio of CSCT students (Adam Jackson, Suzy Wallace and I) attended the 6th European Kesterite Workshop at Northumbria University, Newcastle.

A little bit of background about us; all three of us are working with an earth-abundant, non-toxic photovoltaic material called kesterite, which is made from copper, zinc, tin and sulphur. Adam also attended the workshop two years ago in Berlin.

There was a student workshop the day before the actual conference, where more experienced students in this field, including Adam, gave talks on their work. They also offered help and gave feedback on experimental results other students brought, which I found very useful.

Adam sharing his experience on CZTS

Adam sharing his experience on CZTS

The first day of the conference was packed with talks, from device performance and material properties, to structural properties, defects, ordering-disordering phenomena, and finally device architecture and interfaces. Since all the talks were about kesterite and very relevant to all, the concentration required resulted into coffee running out very quickly during breaks. The majority of speakers were from IREC and HZB, who hosted the workshop in 2011 and 2013 respectively. They are also the key players in this field in Europe.

There was a poster session before the conference dinner. Suzy's poster, which was about using computational chemistry to calculate disorder and inhomogneity in kesterite solar cell, had attracted a lot of attention.

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Poster session

The second day started with a technical problem (something that happens in a lot of conferences!). The good thing about that was, the organiser then combined two parallel discussion groups together. Being in the discussion group was like watching season 5 of a TV series before watching the previous seasons! VOC deficit is still a major issue of this material, and unfortunately, no one is able to solve this problem just yet. We also pointed out the band gap varies with different measuring techniques, which made direct comparison between different devices impossible.

Before I could head back to my lab to try out all those new ideas from this conference, I went to another conference in the United States. Watch this space for another blog from me soon!

Mako is working towards his PhD on "Solution-processed solar cells from earth-abundant elements" with Professor Mark Weller, Dr Aron Walsh and Dr Philip Shields.

 

IUMRS-ICAM 2015 - Culture, Climbing and Conferences.

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📥  Seminars & Conferences

The following blog is contributed by Suzy Wallace from the 2014 Cohort.


On the 26th of October I presented my research on the potential earth abundant and non-toxic solar cell absorber material CZTS (Cu2ZnSnS4) at the IUMRS-ICAM 2015 conference for materials research on Jeju Island in South Korea. We attended three days of the conference where research was focused on a wide variety of different advanced, nanostructured and novel materials for various applications.

Wearable thermoelectric devices seemed to be quite a popular topic! A thermoelectric material is able to use a temperature difference to generate electricity, so the idea would be to use your own body heat to, for example, charge your phone! Research therefore was focused not only on making the devices more efficient and cheap but also to be flexible and durable. Conveniently, Jeju also happens to be a tourist hot-spot at the southernmost part of South Korea and a great place for hiking! So I managed to squeeze in a quick half day of hiking up Hallasan Mountain on our last day on the Island before we headed back to the mainland to visit universities in the capital city, Seoul.

Suzy1

 

What a city Seoul is! I could write a whole blog just on Seoul alone but I’ll try to refrain.

Whilst in Seoul we visited two research groups, that of Professor Aloysius Soon at Yonsei University and that of Professor William Jo at Ewha Women’s University. Professor Soon’s group are focusing on computational research on nanomaterials and Professor Jo’s group synthesise and characterise the solar cell materials that we model computationally in my research group. Both groups made us feel incredibly welcome and all the discussions provided lots of opportunities to ask questions both about the Science and Korean history and culture. I particularly liked when one of Professor Soon’s students (John) was explaining to me how to pronounce bibimbap (a very tasty Korean rice dish that can be served in a hot or cold pot bowl with all sorts of additions such as egg, vegetables, meat, seafood, kimchi and hot sauce), he told me to say the middle syllable as ‘bim like electron beam’.

I also thought that Professor Soon’s description of Seoul summed it up pretty well  – convenient. There’s so much to see and do and everything is easy to get to using the subway, the food was great and you could get food pretty much anywhere and anytime. The people were really friendly and there was a really interesting fusion of old and new with remainders of the old city walls (referred to as the gates) dotted around the city next to big sky scrapers (the Dongdaemun gate is shown in a photo below).

Another great aspect of Seoul for me was the close proximity of yet more mountains! So I was able to go to Bukhansan National Park for rock climbing at the weekend… and as it was Halloween some fancy dress was also involved. When I was out-and-about climbing and sightseeing at the weekend, I spoke to quite a few different people and was struck by just how interested people are in scientific research, especially when it relates to the environment. I chatted to some American tourists while I was looking for a particular tourist attraction in Seoul (Namsan Tower), and it turned out that they were members of an environmental organisation back in the states. Then, when I was out with the climbers and the topic of ‘what do you do’ came up in conversation, we got to have some really interesting discussions on the way up to our climbing route (and also whilst drinking some Korean beer and soju after!). I even heard about a new energy technology for the first time from a couple of the climbers – supercapacitors – so I scurried off to google them to learn more the next day!

So I’d say you learn a lot from listening to talks at conferences and engaging in discussions there as well as during university visits, but there’s also no need to limit yourself to only talking about Science there! Even during the 12 hour flight back from Seoul I had an interesting conversation whilst queuing for the loo with someone from IBM on how Watson (the question answering computer system designed to answer questions posed in natural language) could be really useful for helping scientists to keep up to date on rapidly developing areas of research (perovskite solar cells sprung to my mind immediately!).

It’s surprising just how many people are interested in scientific research and how much you can learn in rather unusual settings!

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Suzy is working towards her PhD on 'Overcoming the efficiency bottleneck of metal sulfide solar cells' with Professor Aron Walsh, Professor Chris Bowen and Professor Mark Weller

Conference report: Materials Research Society Spring Meeting 2014

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📥  Seminars & Conferences

On 21-25th April 2014, DTC student David Miles presented his research at the Materials Research Society (MRS) Spring Meeting held in San Francisco, USA. Attendance of the conference was funded in part due to a successful £750 grant application to the Royal Society of Chemistry. This is his report.

Once a year researchers from across the world descend on San Francisco to hear the latest results in the field of materials science and technology. The MRS Spring Meeting is comprised of 57 parallel symposia over 5 days, covering a huge range of materials research from battery technology to biomaterials. With around 6,000 attendees the conference was an exciting place to share my latest research results as well as see some of the leading academics in my research field.

My oral presentation, titled “Dye-sensitized solar cells using anodized ZnO nanowires”, was presented within the Inorganic and Organic Materials for Dye-Sensitized Solar Cells symposium and was well received by the audience. In addition to hearing about the latest research in the field of solar energy I managed to attend talks on new energy storage technologies and on everyone’s favourite nanomaterial, graphene.

Overall, the conference was a great experience and I came away from it with new research ideas and new connections from institutions around the world. Thanks must be given to the Royal Society of Chemistry Materials Division who generously provided me with a £750 international travel grant to attend this conference.

David is in the second year of his PhD, supervised by Dr Davide Mattia (Chemical Engineering) & Dr Petra Cameron (Chemistry).

 

Conference report: the 4th European Kesterite Workshop

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📥  Seminars & Conferences

The European Kesterite workshops is a fairly young and rapidly-growing event series. Kesterite solar cells with the formula Cu2ZnSn(S,Se)4 are a long-term candidate for terawatt "country-scale" solar generation. Third-year DTC student Adam Jackson attended this year's meeting to support his PhD project and share some early results.

BESSY

BESSY II synchrotron building, Aldershof (photo by duesentrieb via Flickr)

Helmholtz-Zentrum Berlin took their turn in hosting the event at Adlershof on the same site as the BESSY II synchrotron. The meeting was a rare opportunity as a student to hear about the day-to-day challenges of producing samples; not all "common knowledge" is publishable! In general this was a "no cameras" event, offering a preview of the next few months' research papers. While the great advantage of kesterite solar cells is that nominally they are expected to be very cheap, at this stage the material is proving extremely difficult to produce consistently at high quality.

Even with numbers restricted to "active" participants, there were around 80 delegates and a new pre-workshop was introduced this year for PhD students. This gave the 40 students a chance to have some structured discussion; I was also invited to give a talk on this day. Although I was the only computational chemist in the room, this was a very friendly audience and a few useful ideas emerged from the discussion.

All in all, the workshop was a valuable experience; as well as providing useful information, such events are a good way into the international research community. It exposed me to some frank context and personalities that are hard to glean purely from reading the literature.

Conference report: Energy CDT network

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📥  Seminars & Conferences

In September, David Miles and Lisa Sargeant travelled to Imperial College London for the annual Energy Centres for Doctoral Training (CDT) Network conference. The aim of this conference was to enable students from the various different energy-related CDTs to present their research and hear about some of the latest research across the field of energy.

The talks spanned a wide range of areas related to energy, from nuclear fusion to the energy efficiency of hospital buildings. David Miles presented in the Renewable Energy session of the conference, talking about his research on nanomaterials for dye-sensitized solar cells. Lisa Sargeant also represented the CSCT by presenting a poster titled “Waste to wealth: cultivating renewable lipids from the oleaginous yeast, Rhodotorula glutinis”.

Making an unusual addition during the talks, graphic facilitator Eleanor Beer transformed the presentations into cartoons. She created four different pieces, each representing one of the conference’s four themes: Renewable Energy, Efficiency & CO2 Reduction, Energy Storage & Systems, and Nuclear. A number of talks were also given by some of the MSc students from the Energy Futures lab based within Imperial College London.

The cartoon summaries of the talks can be seen below courtesy of Eleanor Beer and the Network of Energy Centres for Doctoral Training.

 

UK-China workshop on the chemistry and physics of functional materials

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📥  Seminars & Conferences

On Monday 28 and Tuesday 29 January 2013, our student Ibbi Ahmet attended a Theo Murphy international scientific meeting held by The Royal Society, which "intended to be pivotal events of lasting significance."

This report comes from second-year DTC student Ibbi Ahmet.

TheoMurphy-1The UK-China workshop was excellent and showcased cutting edge knowledge, which brought together researchers from both China and the UK to present new and interesting concepts on a range of functional materials, addressing both the organic and inorganic fields.

The conference was held at the beautiful location of Chicheley Hall close to Milton Keynes. There were a range of speakers and audience members that had eminent status in their field of research and impressive career successes.

I especially enjoyed the talk by Professor Clare Grey from the University of Cambridge, who presented some excellent concepts that used in-situ solid state NMR to characterise local structural changes in lithium ion batteries, specifically investigating the process of intercalating ions in silicon anodes and lithium air cathodes. The time-lapsed examination of in-situ rather than ex-situ charging of materials in the solid state presented interesting evidence of a multi-step intercalation processes, which can help develop and improve novel battery design as well as our understanding of cathode and anode materials.

TheoMurphy-2Professor Sir Richard Friend, from the University of Cambridge, presented an interesting mode towards high efficiency solar cells. He showed that using materials that had a triplet exciton energy less than one half of the singlet exciton energy will favour the fission of a singlet exciton to a pair of triple excitons (a “two for one offer!!”). This can result in an enhanced solar conversion efficiency beyond the theoretical single junction Shockley-Quessier limit (33.7% to c.a. 48%). He also demonstrated how this phenomenon occurs in a pentacene/leadselenide hybrid low band gap solar cell device.

Professor Richard Catlow, from UCL, showed how computational techniques can be used to understand defect and electron processes in doped semiconducting materials. One fascinating topic of discussion was around p-type ZnO semiconducting materials: It was shown, by calculating the energetics of producing an oxygen vacancy or electron hole within a ZnO lattice, that an oxygen vacancy will be more favourable. This provides evidence for why it is difficult to produce good ZnO p-type semiconductors. He went on to explain why research will need to look towards producing ZnO materials that stabilise the electron hole process and destabilise the process of forming oxygen vacancies.

TheoMurphy-3Another talk, presented by Professor Yunqi Liu, was titled ‘Controllable synthesis of graphene by chemical vapour deposition method and studies on its electronic properties’. There were many techniques shown to be valuable for my research, such as growing high quality graphene onto a range of substrates including ruthenium crystals. It was then shown that graphene can undergo an interesting annealing process resulting in the intercalation of different materials between graphene sheets.

Overall I felt that the conference was very educational and presented interesting experiments and research concepts that can be used to investigate a number of important functional materials in which the properties are not yet well known.

 

October 2011 Symposium: "Photovoltaics— the future is bright"

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📥  Seminars & Conferences

The Centre for Sustainable Chemical Technologies continued its on-going tradition of hosting world-leading symposia last week with “Photovoltaics— the future is bright”.

Over 100 registered attendees took part in the event, including staff and students from various departments of the University of Bath and even a few external visitors. Speakers ranged from theoretical chemists to process engineers from both industry and academia, providing insight into the scientific challenges and opportunities in one of the most active fields of science today.

The University of Bath’s very own Professor Laurie Peter wrapped up the day by returning focus to the principal theme of the centre: sustainability. Many issues experienced in the field were discussed, including the availability of elements and energy payback times, providing ample food for thought over delicious nibbles and drinks!

Special thanks are extended to the students who organised the event as well as all the speakers for making it such a success.