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    Photovoltaic Cells

     Aug 29, 2013

    Photovoltaic Cells - Discovery of Photovoltaic Effect - Photovoltaic Effect Alexandre Edmond Becquerel 1839. At age 19, Bequerel built the world's first photovoltaic: silver-chloride connected to platinum electrodes in an acidic solution. When illuminated, it generated photovoltage and photocurrent. 2 Power generation In 1954 at Bell Laboratories, Developed as “Bell Solar Battery” for telecommunication in tropical rain forest. Silicon p-n junction at 6% efficiency.Use in Space In 1958, US first satellite with solar cells “Vanguard 1.” Worked for 6 years. Semiconductor’s theory - Electron energy levels bounded in a crystal. Particle Statistics - multiple electron can occupy one microstate (quantum state) and the electrons are distingui shable. 2) Bose-Einstein statistics:multiple electron can occupy one microstate and the electrons are undistinguishable. 3) Fermi-Dirac statistics:no two electron can occupy one microstate and the electrons are undistinguishable. (appropriate for metal) 6 electrons are undistinguishable. (appropriate for metal) Fermi-Dirac distribution function - Carrier density - Carrier density 8 (a) Carrier density: n(E)=g(E)f(E)(b) Density of state (number density of the rooms) :g(E) (c) F-D Distribution function:f(E) p-type and n-type semiconductors - adding an impurity of valence-five elements - Majority carriers (electrons) excited at the donor level. - adding an impurity of valence-three elements - Majority carriers (holes) at the accepter level. Production, Conduction and Loss of minority carriers. 2. Semiconductor’s internal photo-electric effects. Photo-voltaic effect. 1) Semiconductor internal electric field Minority carriers is extracted by the internal electric field on semiconductor junction surface 14 2) Dember effect 3) Photo-Electro-Magnetic effect 4) Photon drag effect. 3. Solar cell structure and operational principle.

    Important Tags: Photovoltaic Cells, Solar cell, Discovery of Photovoltaics, Photovoltaics Effects
    Views: 3112
    Domain: Electronics
    Category: Semiconductors

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