0:00:01.938,0:00:04.705
You may have noticed[br]that I'm wearing two different shoes.

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It probably looks funny --

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it definitely feels funny --

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but I wanted to make a point.

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Let's say my left shoe corresponds[br]to a sustainable footprint,

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meaning we humans consume[br]less natural resources

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than our planet can regenerate,

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and emit less carbon dioxide[br]than our forests and oceans can reabsorb.

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That's a stable and healthy condition.

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Today's situation[br]is more [like] my other shoe.

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It's way oversized.

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At the second of August in 2017,

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we had already consumed all resources[br]our planet can regenerate this year.

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This is like spending all your money[br]until the 18th of a month

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and then needing a credit[br]from the bank for the rest of the time.

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For sure, you can do this[br]for some months in a row,

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but if you don't change your behavior,

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sooner or later,[br]you will run into big problems.

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We all know the devastating effects[br]of this excessive exploitation:

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global warming,

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rising of the sea levels,

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melting of the glaciers and polar ice,

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increasingly extreme[br]climate patterns and more.

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The enormity of this problem[br]really frustrates me.

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What frustrates me even more[br]is that there are solutions to this,

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but we keep doing things[br]like we always did.

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Today I want to share with you

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how a new solar technology can contribute[br]to a sustainable future of buildings.

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Buildings consume about 40 percent[br]of our total energy demand,

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so tackling this consumption

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would significantly reduce[br]our climate emissions.

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A building designed[br]along sustainable principles

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can produce all the power[br]it needs by itself.

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To achieve this,

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you first have to reduce[br]the consumption as much as possible,

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by using well-insulated walls[br]or windows, for instance.

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These technologies[br]are commercially available.

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Then you need energy[br]for warm water and heating.

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You can get this[br]in a renewable way from the sun

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through solar-thermal installations

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or from the ground and air,[br]with heat pumps.

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All of these technologies are available.

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Then you are left[br]with the need for electricity.

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In principle, there are several ways[br]to get renewable electricity,

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but how many buildings do you know[br]which have a windmill on the roof,

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or a water power plant in the garden?

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Probably not so many, because usually,[br]it doesn't make sense.

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But the sun provides abundant energy[br]to our roofs and facades.

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The potential to harvest this energy[br]at our buildings' surfaces is enormous.

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Let's take Europe as an example.

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If you would utilize all areas[br]which have a nice orientation to the sun

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and they're not overly shaded,

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the power generated by photovoltaics

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would correspond to about 30 percent[br]of our total energy demand.

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But today's photovoltaics[br]have some issues.

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They do offer a good[br]cost-performance ratio,

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but they aren't really flexible[br]in terms of their design,

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and this makes aesthetics a challenge.

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People often imagine pictures like this

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when thinking about[br]solar cells on buildings.

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This may work for solar farms,

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but when you think of buildings,[br]of streets, of architecture,

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aesthetics does matter.

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This is the reason why we don't see[br]many solar cells on buildings today.

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They just don't match.

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Our team is working on a totally[br]different solar-cell technology,

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which is called[br]organic photovoltaics or OPV.

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The term organic describes

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that the material used[br]for light absorption and charge transport

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are mainly based on the element carbon,

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and not on metals.

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We utilize the mixture of a polymer

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which is set up by different[br]repeating units,

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like the pearls in a pearl chain,

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and a small molecule[br]which has the shape of a football

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and is called fullerene.

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These two compounds are mixed[br]and dissolved to become an ink.

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And like ink,

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they can be printed with simple[br]printing techniques like slot-die coating

0:04:02.044,0:04:05.855
in a continuous roll-to-roll process[br]on flexible substrates.

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The resulting thin layer[br]is the active layer,

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absorbing the energy of the sun.

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This active layer is extremely effective.

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You only need a layer thickness[br]of 0.2 micrometers

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to absorb the energy of the sun.

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This is 100 times thinner[br]than a human hair.

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To give you another example,

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take one kilogram of the basic polymer

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and use it to formulate the active ink.

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With this amount of ink,

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you can print a solar cell[br]the size of a complete football field.

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So OPV is extremely material efficient,

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which I think is a crucial thing[br]when talking about sustainability.

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After the printing process,

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you can have a solar module[br]which could look like this ...

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It looks a bit like a plastic foil,

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and actually has many of its features.

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It's lightweight ...

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it's bendable ...

0:05:02.458,0:05:04.181
and it's semitransparent.

0:05:06.949,0:05:09.329
But it can harvest the energy[br]of the sun outdoors

0:05:09.353,0:05:10.824
and also of this indoor light,

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as you can see with this small,[br]illuminated LED.

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You can use it in its plastic form

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and take advantage of its low weight[br]and its bendability.

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The first is important when thinking[br]about buildings in warmer regions.

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Here, the roofs are not designed[br]to bear additionally heavy loads.

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They aren't designed[br]for snow in winter, for instance,

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so heavy silicon solar cells[br]cannot be used for light harvesting,

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but these lightweight solar foils[br]are very well suited.

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The bendability is important

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if you want to combine the solar cell[br]with membrane architecture.

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Imagine the sails[br]of the Sydney Opera as power plants.

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Alternatively, you can[br]combine the solar foils

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with conventional construction[br]materials like glass.

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Many glass facade elements[br]contain a foil anyway,

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to create laminated safety glass.

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It's not a big deal to add[br]a second foil in the production process,

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but then the facade element[br]contains the solar cell

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and can produce electricity.

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Besides looking nice,

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these integrated solar cells come along[br]with two more important benefits.

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Do you remember the solar cell[br]attached to a roof I showed before?

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In this case, we install the roof first,

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and as a second layer, the solar cell.

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This is adding on the installation costs.

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In the case of integrated solar cells,

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at the site of construction,[br]only one element is installed,

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being at the same time[br]the envelope of the building

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and the solar cell.

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Besides saving on the installation costs,

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this also saves resources,

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because the two functions[br]are combined into one element.

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Earlier, I've talked about optics.

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I really like this solar panel --

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maybe you have different taste[br]or different design needs ...

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No problem.

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With the printing process,

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the solar cell can change[br]its shape and design very easily.

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This will give the flexibility[br]to architects,

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to planners and building owners,

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to integrate this electricty-producing[br]technology as they wish.

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I want to stress that this is not[br]just happening in the labs.

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It will take seven more years[br]to get to mass adoption,

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but we are at the edge[br]of commercialization,

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meaning there are several companies[br]out there with production lines.

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They are scaling up their capacities,

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and so are we, with the inks.

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(Shoe drops)

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This smaller footprint[br]is much more comfortable.

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(Laughter)

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It is the right size, the right scale.

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We have to come back to the right scale[br]when it comes to energy consumption.

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And making buildings carbon-neutral[br]is an important part here.

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In Europe,

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we have the goal to decarbonize[br]our building stock until 2050.

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I hope organic photovoltaics[br]will be a big part of this.

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Here are a couple of examples.

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This is the first commercial installation[br]of fully printed organic solar cells.

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"Commercial" means that the solar cells[br]were printed on industrial equipment.

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The so-called "solar trees"[br]were part of the German pavilion

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at the World Expo in Milan in 2015.

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They provided shading during the day

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and electricity[br]for the lighting in the evening.

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You may wonder why this hexagonal shape[br]was chosen for the solar cells.

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Easy answer:

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the architects wanted to have[br]a specific shading pattern on the floor

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and asked for it,

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and then it was printed as requested.

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Being far from a real product,

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this free-form installation hooked[br]the imagination of the visiting architects

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much more than we expected.

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This other application[br]is closer to the projects

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and applications we are targeting.

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In an office building[br]in São Paulo, Brazil,

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semitransparent OPV panels[br]are integrated into the glass facade,

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serving different needs.

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First, they provided shading[br]for the meeting rooms behind.

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Second, the logo of the company[br]is displayed in an innovative way.

0:09:12.644,0:09:14.533
And of course, electricity is produced,

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reducing the energy footprint[br]of the building.

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This is pointing towards a future

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where buildings are no longer[br]energy consumers,

0:09:21.893,0:09:23.309
but energy providers.

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I want to see solar cells[br]seamlessly integrated

0:09:26.923,0:09:28.802
into our building shells

0:09:28.826,0:09:31.878
to be both resource-efficient[br]and a pleasure to look at.

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For roofs, silicon solar cells[br]will often continue to be a good solution.

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But to exploit the potential[br]of all facades and other areas,

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such as semitransparent areas,

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curved surfaces and shadings,

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I believe organic photovoltaics[br]can offer a significant contribution,

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and they can be made in any form[br]architects and planners will want them to.

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Thank you.

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(Applause)