The Green River Organic Photovoltaic Project Werner Heisenberg Nobel Prize Lecture 1933

The Green River Organic Photovoltaic Project Light meets matter From atomic spectra to photovoltaic cells. Keith Clay, Green River Community College

The Green River Organic Photovoltaic Project Famous inventions We are interested in… Photovoltaic devices produce electricity from light.

The Green River Organic Photovoltaic Project Famous inventions We are interested in… Photovoltaic devices produce electricity from light. What does exactly the opposite?

The Green River Organic Photovoltaic Project Famous inventions We are interested in… Photovoltaic devices produce electricity from light. What does exactly the opposite?

The Green River Organic Photovoltaic Project Famous inventions We are interested in… Photovoltaic devices produce electricity from light. What does exactly the opposite?

The Green River Organic Photovoltaic Project About light bulbs CFLs use 20% to 30% as much power. They contain mercury… but so does coal. Incandescent or “traditional” Compact fluorescent or “CFL” How do they work?

The Green River Organic Photovoltaic Project About light bulbs Scientists learn about light sources by studying the kinds of “light” they produce. This is called looking at the “spectrum” of the light source.

The Green River Organic Photovoltaic Project About light bulbs We can view the visible spectrum with prisms

The Green River Organic Photovoltaic Project About light bulbs We can study the spectrum with diffraction gratings

The Green River Organic Photovoltaic Project About light bulbs

The Green River Organic Photovoltaic Project About light bulbs

The Green River Organic Photovoltaic Project About light bulbs

The Green River Organic Photovoltaic Project About light bulbs

The Green River Organic Photovoltaic Project Quantum Mechanics Werner Heisenberg Nobel Prize Lecture 1933

The Green River Organic Photovoltaic Project Quantum Mechanics Werner Heisenberg 1933

The Green River Organic Photovoltaic Project Quantum Mechanics Neils Bohr 1913

The Green River Organic Photovoltaic Project Quantum Mechanics The Bohr Model of the Atom Hydrogen A proton An electron

The Green River Organic Photovoltaic Project Quantum Mechanics The Bohr Model of the Atom

The Green River Organic Photovoltaic Project Quantum Mechanics The Bohr Model of the Atom

The Green River Organic Photovoltaic Project Quantum Mechanics An atomic system is capable of assuming only discrete states.

The Green River Organic Photovoltaic Project Quantum Mechanics An atomic system is capable of assuming only discrete states. This is allowed This is not

The Green River Organic Photovoltaic Project Quantum Mechanics Quantum states

The Green River Organic Photovoltaic Project Quantum Mechanics Quantum states

The Green River Organic Photovoltaic Project Quantum Mechanics Discrete Energy Levels

The Green River Organic Photovoltaic Project Quantum Mechanics

The Green River Organic Photovoltaic Project Quantum Mechanics Neils Bohr 1913

The Green River Organic Photovoltaic Project Quantum Mechanics

The Green River Organic Photovoltaic Project Quantum Mechanics photon

The Green River Organic Photovoltaic Project Quantum Mechanics

The Green River Organic Photovoltaic Project Quantum Mechanics photon

The Green River Organic Photovoltaic Project Quantum Mechanics Bohr Atom 1913 Quantum Mechanics a century later

The Green River Organic Photovoltaic Project Quantum Mechanics Quantum Mechanics a century later An atomic system is capable of assuming only discrete states.

The Green River Organic Photovoltaic Project Quantum Mechanics photon

The Green River Organic Photovoltaic Project Quantum Mechanics

The Green River Organic Photovoltaic Project Quantum Mechanics Run electric current through hydrogen gas

The Green River Organic Photovoltaic Project Quantum Mechanics Atomic spectrum of hydrogen

The Green River Organic Photovoltaic Project Quantum Mechanics 434 nm486 nm656 nm Atomic spectrum of hydrogen

The Green River Organic Photovoltaic Project Quantum Mechanics photon

The Green River Organic Photovoltaic Project Quantum Mechanics photon

The Green River Organic Photovoltaic Project Quantum Mechanics 434 nm486 nm656 nm n = 3 to n = 2 Atomic spectrum of hydrogen

The Green River Organic Photovoltaic Project Quantum Mechanics 434 nm486 nm656 nm n = 3 to n = 2n = 4 to n = 2n = 5 to n = 2 Atomic spectrum of hydrogen

The Green River Organic Photovoltaic Project Atomic Spectra A strange looking light bulb. How does it work?

The Green River Organic Photovoltaic Project Atomic Spectra

The Green River Organic Photovoltaic Project Atomic Spectra Atomic spectrum of neon

The Green River Organic Photovoltaic Project Atomic Spectra How does a fluorescent light bulb work?

The Green River Organic Photovoltaic Project Atomic Spectra Atomic spectrum of mercury:

The Green River Organic Photovoltaic Project Atomic Spectra Atomic spectrum of mercury: Visible spectrum of CFL: mercuryphosphors

The Green River Organic Photovoltaic Project Atomic Spectra mercuryphosphors All five colors blended together

The Green River Organic Photovoltaic Project Atomic Spectra An electrified gas through rainbow glasses Atomic spectrum of helium

The Green River Organic Photovoltaic Project Atomic Spectra helium hydrogen neon carbon iron

The Green River Organic Photovoltaic Project Atomic Spectra

The Green River Organic Photovoltaic Project Atomic Spectra Molecular Carbon dioxide

The Green River Organic Photovoltaic Project Atomic Spectra Molecular Water

The Green River Organic Photovoltaic Project Energy diagrams

The Green River Organic Photovoltaic Project Energy diagrams

The Green River Organic Photovoltaic Project Energy diagrams Energy states of the hydrogen atom Increasing energy  Increasing angular momentum 

The Green River Organic Photovoltaic Project Energy diagrams = 400 nm = 550 nm = 700 nm E = 3.1 eV E = 2.3 eV E = 1.8 eV E = 3.6 eV = 340 nm = 230 nm E = 5.4 eV Cast of characters: The photons Simplified

The Green River Organic Photovoltaic Project Energy diagrams Energy states of a simplified system E = 0.0 eV(“Ground state”) E = 5.4 eV E = 2.3 eV E = 1.8 eV Each orbital can hold two electrons = an electron = another electron = a pair of electrons Simplified

The Green River Organic Photovoltaic Project Light meets matter Energy states of a simplified system E = 5.4 eV = 230 nm UV photon E = 0.0 eV E = 5.4 eV E = 2.3 eV E = 1.8 eV Shine a UV light on our system

The Green River Organic Photovoltaic Project Light meets matter Energy states of a simplified system E = 5.4 eV = 230 nm UV photon E = 2.3 eV E = 1.8 eV E = 5.4 eV E = 0.0 eV

The Green River Organic Photovoltaic Project Light meets matter Energy states of a simplified system E = 5.4 eV = 230 nm UV photon E = 2.3 eV E = 1.8 eV E = 5.4 eV E = 0.0 eV

The Green River Organic Photovoltaic Project Light meets matter Energy states of a simplified system = an “electron hole” Electron holes Have positive charge Have mass Move through materials much as electrons do E = 2.3 eV E = 1.8 eV E = 5.4 eV E = 0.0 eV

The Green River Organic Photovoltaic Project Light meets matter Energy states of a simplified system What happens next? Possibility #1: E = 5.4 eV = 230 nm E = 2.3 eV E = 1.8 eV E = 5.4 eV E = 0.0 eV

The Green River Organic Photovoltaic Project Light meets matter Energy states of a simplified system What happens next? Possibility #1: E = 5.4 eV = 230 nm E = 2.3 eV E = 1.8 eV E = 5.4 eV E = 0.0 eV

The Green River Organic Photovoltaic Project Light meets matter Energy states of a simplified system What happens next? Possibility #1: E = 2.3 eV E = 1.8 eV E = 5.4 eV E = 0.0 eV “Nothing happened”

The Green River Organic Photovoltaic Project Light meets matter What happens next? REFLECTION: Absorption and re-emission of the same type of photon.

The Green River Organic Photovoltaic Project Light meets matter What happens next? REFLECTION: Absorption and re-emission of the same type of photon.

The Green River Organic Photovoltaic Project Light meets matter Energy states of a simplified system What happens next? Possibility #2: E = 3.6 eV = 340 nm E = 2.3 eV E = 1.8 eV E = 5.4 eV E = 0.0 eV

The Green River Organic Photovoltaic Project Light meets matter Energy states of a simplified system What happens next? Possibility #2: E = 1.8 eV = 700 nm E = 2.3 eV E = 1.8 eV E = 5.4 eV E = 0.0 eV

The Green River Organic Photovoltaic Project Light meets matter Energy states of a simplified system What happens next? Possibility #2: = 700 nm Light absorbed = 230 nm Light emitted = 340 nm E = 2.3 eV E = 1.8 eV E = 5.4 eV E = 0.0 eV

The Green River Organic Photovoltaic Project Light meets matter What happens next? Possibility #1: = 700 nm Light absorbed = 230 nm Light emitted = 340 nm Invisible Visible

The Green River Organic Photovoltaic Project Light meets matter What happens next? FLUORESCENCE: Absorption of UV light and immediate emission of visible light. Fluorescence ends when the light source is removed.

The Green River Organic Photovoltaic Project Light meets matter Energy states of a simplified system What happens next? Possibility #3: E = 3.1 eV = 400 nm E = 2.3 eV E = 1.8 eV E = 5.4 eV E = 0.0 eV

The Green River Organic Photovoltaic Project Light meets matter Energy states of a simplified system What happens next? Possibility #3: E = 2.3 eV = 550 nm E = 2.3 eV E = 1.8 eV E = 5.4 eV E = 0.0 eV Unlikely? Slow?

The Green River Organic Photovoltaic Project Light meets matter Energy states of a simplified system What happens next? Possibility #3: E = 2.3 eV E = 1.8 eV E = 5.4 eV E = 0.0 eV = 550 nm Light absorbed = 230 nm Light emitted = 400 nm Immediate Delayed

The Green River Organic Photovoltaic Project Light meets matter What happens next? Possibility #3: = 550 nm Light absorbed = 230 nm Light emitted = 400 nm Invisible Visible Immediate Fluorescence Visible Delayed Phosphorescence

The Green River Organic Photovoltaic Project Light meets matter What happens next? Phosphorescence: Delayed emission of visible light after absorption of UV light. Phosphorescence continues after the UV energy source is removed. CFL bulbs glow after they are turned off!

The Green River Organic Photovoltaic Project Light meets matter Energy states of a simplified system E = 0.0 eV E = 5.4 eV E = 2.3 eV E = 1.8 eV Three processes: 1)Reflection

The Green River Organic Photovoltaic Project Light meets matter Three processes: 1)Reflection 2)Fluorescence Energy states of a simplified system E = 2.3 eV E = 1.8 eV E = 5.4 eV E = 0.0 eV

The Green River Organic Photovoltaic Project Light meets matter Three processes: 1)Reflection 2)Fluorescence 3)Phosphorescence Energy states of a simplified system E = 2.3 eV E = 1.8 eV E = 5.4 eV E = 0.0 eV

The Green River Organic Photovoltaic Project Light meets matter Three processes: 1)Reflection 2)Fluorescence 3)Phosphorescence Energy states of a simplified system E = 2.3 eV E = 1.8 eV E = 5.4 eV E = 0.0 eV All processes happen at once in different atoms

The Green River Organic Photovoltaic Project Photovoltaic cells All processes happen at once in different atoms To make a photovoltaic cell: Add another process… that forces the electron to move… so we can capture the energy of the absorbed photon.

The Green River Organic Photovoltaic Project Photovoltaic cells To make a photovoltaic cell: Add another process… that forces the electron to move… so we can capture the energy of the absorbed photon.

The Green River Organic Photovoltaic Project Photovoltaic cells To make a photovoltaic cell: Add another process… that forces the electron to move… so we can capture the energy of the absorbed photon. Cathode Anode Donor Acceptor Junction

The Green River Organic Photovoltaic Project Photovoltaic cells Photon: excites an electron in the donor. Donor: gives up the electron to the acceptor. Acceptor: accepts the electron from the donor. Anode: electrons flow OUT of the anode. Cathode: electrons flow INTO the cathode. Junction: the surface between donor and acceptor Cathode Anode Donor Acceptor Junction

The Green River Organic Photovoltaic Project Cathode Anode Donor Acceptor Junction DonorAcceptor Energy levels Electron = Hole = or Cathode Anode Photovoltaic cells “Highest Occupied Molecular Orbitals”

The Green River Organic Photovoltaic Project Cathode Anode Donor Acceptor Junction DonorAcceptor Energy levels Electron = Hole = or Cathode Anode Photovoltaic cells “Lowest Unoccupied Molecular Orbitals”

The Green River Organic Photovoltaic Project Sunlight Cathode Anode Donor Acceptor Junction DonorAcceptor Energy levels Electron = Hole = or Cathode Anode Photovoltaic cells

The Green River Organic Photovoltaic Project Energy levels - + Cathode Anode Donor Acceptor Junction DonorAcceptor Electron = Hole = or Cathode Photovoltaic cells Anode

The Green River Organic Photovoltaic Project Energy levels - + Cathode Anode Donor Acceptor Junction DonorAcceptor Electron = Hole = or Cathode Photovoltaic cells Anode

The Green River Organic Photovoltaic Project Cathode Anode Donor Acceptor Junction Energy levels DonorAcceptor Electron = Hole = or - + Cathode Anode Photovoltaic cells

The Green River Organic Photovoltaic Project Cathode Anode Donor Acceptor Junction Energy levels DonorAcceptor Electron = Hole = or - + Cathode Anode Photovoltaic cells

The Green River Organic Photovoltaic Project Cathode Anode Donor Acceptor Junction Energy levels DonorAcceptor Electron = Hole = or - + Cathode Anode Photovoltaic cells

The Green River Organic Photovoltaic Project Cathode Anode Donor Acceptor Junction Energy levels DonorAcceptor Electron = Hole = or - Cathode Anode Photovoltaic cells +

The Green River Organic Photovoltaic Project Cathode Anode Donor Acceptor Junction Energy levels DonorAcceptor Electron = Hole = or - + Cathode Anode Photovoltaic cells

The Green River Organic Photovoltaic Project Cathode Anode Donor Acceptor Junction Energy levels DonorAcceptor Cathode Anode - Photovoltaic cells +

The Green River Organic Photovoltaic Project Cathode Anode Donor Acceptor Junction Energy levels DonorAcceptor Cathode Anode - Photovoltaic cells +

The Green River Organic Photovoltaic Project Cathode Anode Donor Acceptor Junction Energy levels DonorAcceptor Cathode Anode Photovoltaic cells wire + -

The Green River Organic Photovoltaic Project DonorAcceptor Cathode Anode Photovoltaic cells wire

The Green River Organic Photovoltaic Project Photovoltaic cells Electricity flows in. Quantum states are excited. Light comes out. Light goes in. Quantum states are excited. Electricity comes out.

The Green River Organic Photovoltaic Project Photoelectric megawatts

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