1. Electricity from Light: The Grätzel Cell

2. Electromagnetic Spectrum  -rays X-raysUVIRFMAM Radio Waves Long Radio Waves 400 500 600 700 Wavelength ( ) in nanometers 10 -16 10 -12 10 -02 10 -8 10 -6 10 -4 10 --2 10 0 10 2 10 4 10 8 (m) Increasing Energy — Decreasing Wavelength Microwave

3. Atomic Structure

4. Molecular Structure

5. Subtractive Coloration If one component of white light is removed, the color registered by the eye is the complimentary color (opposite of the color removed).

6. Donor-Acceptor Concept Dye molecules can be broken into three separate pieces: Electron Donor Group Bridge Electron Acceptor Group Lone e - pairs Anions Polar with  - at bridge end A place for the e - to move into higher energy states. Usually part of The donor group Electronegative elements Polar with  - opposite bridge end. Cations

7. Donors Increasing order of efficiency

8. Acceptors Increasing order of efficiency

9. + H 2 O

10. UV/ Visible Spectrophotometer Scan AbsorbanceAbsorbance 1.0 0.8 0.6 0.4 0.2 0.0 350400450500550600650700750 Wavelength in nanometers

11. What would happen if the electrons in the dye molecule where captured and sent through a curcuit?

12. I - /I 3 - Preparation of a Grätzel Cell ITO or FTO ITO or FTO TiO 2 Porphyrin h I SC ~ 20 mA/cm 2 V OC ~ 0.7 Volts  ~ 1 Efficiency ~ 11% Diagram courtesy of Dr. Wamser

13. Operation of a Grätzel Cell ITOTiO 2 TCPP -0.9 +1.1 +2.6 -0.6 V oc = 0.7 V ; I sc = 20 mA/cm 2 I 3 / I ITO +0.2 -- hv Porphyrin LUMO Porphyrin HOMO P+P+P+P+ Diagram courtesy of Dr. Wamser