Electricity from Light: The Grätzel Cell

Electromagnetic Spectrum  -rays X-raysUVIRFMAM Radio Waves Long Radio Waves Wavelength ( ) in nanometers (m) Increasing Energy — Decreasing Wavelength Microwave

Atomic Structure

Molecular Structure

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).

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

Donors Increasing order of efficiency

Acceptors Increasing order of efficiency

+ H 2 O

UV/ Visible Spectrophotometer Scan AbsorbanceAbsorbance Wavelength in nanometers

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

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

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