0:00:01.994,0:00:04.761
You may have noticed[br]that I'm wearing two different shoes.

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It probably looks funny --

0:00:08.518,0:00:10.192
it definitely feels funny --

0:00:10.192,0:00:11.872
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 ocean 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 have already consumed all resources

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our planet can regenerate this year.

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This is like spending all your money[br]until the [eighteenth] 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,

0:00:53.992,0:00:55.939
but if you don't change your behavior,

0:00:55.939,0:00:58.436
sooner or later you will[br]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 climate patterns

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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

0:01:26.477,0:01:29.263
how a new solar technology can contribute

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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 principle

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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 in a renewable[br]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,

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

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but how many buildings do you know

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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[br]usually it doesn't make sense.

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

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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[br]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,

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of streets,

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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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It's just called organic photovoltaics,

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or OPV.

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The term organic describes

0:03:31.480,0:03:33.995
that the material used[br]for light absorption

0:03:33.995,0:03:35.414
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

0:03:42.185,0:03:44.811
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

0:04:02.190,0:04:06.001
in a continuous roll-to-roll process[br]on flexible substrates.

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The resulting thin layer

0:04:08.244,0:04:11.077
is the active layer absorbing[br]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,

0:04:26.943,0:04:29.663
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,

0:04:43.005,0:04:46.295
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

0:04:50.778,0:04:53.195
which could look like this ...

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it looks a bit like a plastic foil,

0:04:55.178,0:04:57.058
and actually has many of its features.

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It's lightweight ...

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it's bendable ...

0:05:02.602,0:05:04.565
and it's semitransparent.

0:05:07.101,0:05:09.504
But it can harvest the energy[br]of the sun outdoors

0:05:09.504,0:05:11.052
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

0:05:16.963,0:05:20.029
and take advantage of its low weight[br]and it's 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 for snow[br]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 cells of the Sydney[br]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 façade 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 façade element[br]contains the solar cell

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and can produce electricity.

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Besides looking nice,

0:06:12.813,0:06:16.990
these integrated solar cells come along[br]with two more important benefits.

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

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In this case,

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we install the roof first,

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and as a second layer,

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the solar cell.

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This is adding on your installation costs.

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In the case of integrated solar cells,

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at the site of construction,

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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 your installation costs,

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this also saves resources

0:06:42.798,0:06:46.086
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

0:07:06.171,0:07:09.844
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,

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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 for[br]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:

0:08:35.060,0:08:38.468
the architects wanted to have[br]a specific shading pattern on the floor

0:08:38.468,0:08:39.757
and asked for it,

0:08:39.757,0:08:41.624
and then it was printed as requested.

0:08:42.348,0:08:44.151
Being far from a real product,

0:08:44.151,0:08:47.864
this free-form installation hooked[br]the imagination of the visiting architects

0:08:47.864,0:08:49.337
much more than we expected.

0:08:49.862,0:08:52.827
This other application[br]is closer to the projects

0:08:52.827,0:08:54.740
and applications we are targeting.

0:08:55.060,0:08:57.968
In an office building[br]in São Paulo, Brazil,

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

0:09:01.736,0:09:03.009
serving different needs.

0:09:03.550,0:09:06.798
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.

0:09:12.708,0:09:14.557
And of course electricity is produced,

0:09:14.557,0:09:16.880
reducing the energy footprint[br]of the building.

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This is pointing towards a future

0:09:19.570,0:09:21.981
where buildings are no longer[br]energy consumers,

0:09:21.981,0:09:23.397
but energy providers.

0:09:24.056,0:09:26.979
I want to see solar cells[br]seamlessly integrated

0:09:26.979,0:09:28.881
into our building shells

0:09:28.881,0:09:31.933
to be both resource-efficient[br]and a pleasure to look at.

0:09:32.676,0:09:36.789
For roofs, silicon solar cells[br]will often continue to be a good solution.

0:09:37.199,0:09:41.714
But to exploit the potential[br]of all façades and other areas,

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such as semitransparent areas,

0:09:44.021,0:09:45.202
curved surfaces

0:09:45.202,0:09:46.704
and shadings,

0:09:46.704,0:09:51.669
I believe organic photovoltaics[br]can offer a significant contribution,

0:09:51.669,0:09:56.873
and they can be made in any form[br]architects and planners will want them to.

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Thank you.

0:09:58.729,0:10:00.436
(Applause)