Juice from Juice - PowerPoint Presentation

Slide1

Juice from JuiceWorkshop Presentation

(Slightly condensed)

Updated April 2015Slide2

Overview of JfJ Project

Goal: develop dye-sensitized solar cell (DSSC) kit that

Supports state science curricula and standards (3

rd – 12th grade)Gets students involved in solar-energy technologyReinforces inquiry-based learning and invites further discussion/investigation from studentsIntegration of three scientific fields under one DSSC unit

Physics

Chemistry

Biology

DSSC

Chemical potential

Electron transfer

Light

absorptionSlide3

DSSCs vs. Traditional

P

hotovoltaics

Solar window prototype by Solaronix - EPFLSony Hana

Akari (“flower light”) lamps: lampshades are

screenprinted DSSCs

Caltech Holliston parking structureSlide4

Today’s Workshop

anthocyanin

TiO

2

surface on FTO glass

h

ν

e

-

“Sandwich” dye-sensitized solar cell

photosensitizer

photo = lightSlide5

DSSC Components

TiO

2

nanoparticle pasteNatural dyes used as photosensitizersChlorophyll (spinach leaves)Anthocyanin (berries, fruits)Betalin (beets)Conductive glass electrodes (FTO)Redox electrolyte (I-/I3-)Light source (projector or sun)

John Muir HS Chemistry student (PUSD)

TiO

2

electrode soaking in crushed berriesSlide6

Assembling the Electrodes

TiO

2

layerTiO2 layer dyed with

blackberry juice

Assembled sandwichCompleted cell with electrolyte in between

the layersGraphite counter electrodeSlide7

This ball has potential energy and can do work by knocking over some dominos at the bottom of the hill

Conceptual DSSC Explanation

The ball is like an electron – we can get the electrons to “roll down a hill” to make electricity!Slide8

Atomic Energy Levels

Energy

1s

2s

2p

First,

consider General

Chemistry’s atomic-orbital energy levels.

Electrons

populate these energy levels, and can be excited to higher energy levels.

We use similar energy diagrams for electrons in molecules and solids, too!Slide9

Extension of Energy Levels to DSSCs

1s

2s

2p

EnergySlide10

Extension of Energy Levels to DSSCs

Energy

TiO

2

Dye

I

-

/I

3

-

1s

2s

2p

EnergySlide11

Electron Transfer

Energy

TiO

2

I

-

/I

3

-

But for our new energy diagram, there is no spatial x-axis dependence, so let’s rearrange the locations to see our analogy better.

In this scheme, we positioned the energy levels to spatially correspond to our materials’ locations.

DyeSlide12

Electron Transfer

TiO

2

Dye

I

-

/I

3

-Load

We also added a load that the electrons pass through, as in the picture.

Although we’ve spatially rearranged the energy levels , they still sit at the same energies!

EnergySlide13

Electron Transfer

TiO

2

Dye

I

-

/I

3

-Load

Light excites the electron in the dye from the dye’s valence band to its conduction band

EnergySlide14

Electron Transfer

TiO

2

Dye

I

-

/I

3

-Load

The electron then ‘rolls down the hill,’ passing through the load ‘knocking over

dominos

,’ then returns to the ground state in the dye

EnergySlide15

Electron Transfer

TiO

2

Dye

I

-

/I

3

-Load

The electron then ‘rolls down the hill,’ passing through the load ‘knocking over

dominos

,’ then returns to the ground state in the dye

EnergySlide16

Electron Transfer

TiO

2

Dye

I

-

/I

3

-Load

The electron then ‘rolls down the hill,’ passing through the load ‘knocking over

dominos

,’ then returns to the ground state in the dye

EnergySlide17

Electron Transfer

Energy

TiO

2

Dye

I

-

/I

3-

Load

The sun does all the work for us! It throws the electrons to the ‘top of the hill,’ while we simply make use of the electrons’ energy as it rolls down! This is our SOLAR ENERGY.Slide18

Electron Transfer

Energy

TiO

2

Dye

I

-

/I

3-

Load

Our load can be a light bulb or other electronic device. Today it is a

multimeter

.Slide19

Chemical Reactions Resulting in

E

lectron

Transfer for Current Flow Image credit: http://chemed.chem.purdue.edu/genchem

/topicreview/bp

/ch19/oxred_2.phpReduction I3

- + 2e-  3I-

w

Oxidation

3I

-  I3- +2e-

-

2 e

-

+

-

LEO the lion goes GER

OIL RIGSlide20

Using M

ultimeters

DC = Direct Current

Variable

Units of Measurement

Context

Current

‘I’

Amps

(A)

= Coulomb/sec

Electron travel rate

Voltage‘V’

Volts (V) = Joules/

Coulomb

‘Push’ [or energy] per electron packet

Resistance

‘R’

Ohms (

Ω

)= Volts/Amps

Opposing

force [like friction in mechanics]

Power

‘P’

Watts (W) = Joules/ sec

= Volts*Amps

Energy transfer rate

P = I*V

Joule’s Law

V = IR

Ohm’s LawSlide21

Why this System?

Materials cheap, abundant, non-toxic

Right energy level alignment of dyes, FTO, TiO

2, I-/I3-, graphiteDetectable I and V Other dyes [other fruits or synthetic dyes] can be used, other metal oxides besides TiO2 can be used; however, energy level alignment and electron transfer rates must be satisfiedSlide22

Sub-Module: Biology

Plants

Solar

Cells

Light Absorber

Molecules

Materials

Fuel Produced

ChemicalElectrical

Fuel StorageYesNo

Chlorophyll and colored markers contain various pigments (chemical compounds) that have different affinities for solid vs. liquid phaseSeparate via thin layer chromatography (TLC)Characterize by R

f valueEffect of color of light on absorptionTLC plateSlide23

Sub-Module: Chemistry

Output voltage due to reduction/oxidation (redox) reactions

Different metals have different reduction potentials

Create activity series using Zn, Cu, Sn, and Mg

E

(V)

-0.5

0.0

0.5

1.0

Galvanic cell

DSSCSlide24

Sub-Module: Physics

Nature of light

White light can be made from individual colors (additive)

Prisms disperse white light into its componentsDark colors absorb some light and transmit/reflect others (subtractive)

Converting light to electricity: solar cells

Conversion efficiency

Output dependence on intensity and color

http://

www.astro.virginia.edu

/~rsl4v/PSC/light.htmlSlide25

Commercial DSSC Kits

Juice from Juice kits distributed by Arbor Scientific

I

ncludes

all materials for the integrated labs we have

developed

DSSC

Fabrication………………..$110Electrochemistry (Chem) & Chromatography (Bio).……….$50

Light & Solar Cells (Phys) ……$70DSSC Refill.………………………...$39 Chem Refill.……………………..…$19Enough materials for a 30 person classMaterials can be reused for several yearsSlide26

“I need help!”

“I don’t have enough $$ for the kit!”

Kids in Need Foundation,

DonorsChoose.org, local power company grantsDonations from parents, PTA, bake salesEven aluminum cans! “I don’t remember how to do it!”YouTube videos and lesson plans onlinehttp://thesolararmy.org/jfromjWe can do a demo at your school!

Email questions – juicefromjuice@caltech.edu“I don’t have time in my curriculum!”

All the labs fulfill state standards!Incorporate as much as you can – some renewable energy education is better than noneSlide27

Conclusions and goals

Integrate basic science with push towards clean energy

Get students and teachers directed toward research in solar energy conversion

Feedback and continued project developmentImprovements to curriculumThanks – and have fun!

Physics

Chemistry

Biology

DSSC

Chemical potential

Electron transfer

Light

absorption

Questions:

JuiceFromJuice@caltech.edu