《!3620504e206a756e6374696f6e》.pdf

Solar cell operating principles Solar cell operation is based on the photovoltaic effect: The generation of a voltage difference at the junction of two different materials in response to visible or other radiation. 1. Absorption of light - Generation of charge carriers 2. Separation of charge carriers 3. Collection of the carriers at the electrodes Solar cell operating principles Thermodynamic approach: Conversion of energy of solar radiation into electrical energy Two-step process: 1. Solar heat →Chemical energy of electron-hole pairs 2. Chemical energy →Electrical energy Solar cell operating principles 1. Solar heat →Chemical energy of electron-hole pairs • Non-equilibrium carrier concentration • Quasi-Fermi energies E E E C C C E FN Eph EF µeh E FP E E E V V V 10-14 s 10-12 s equilibrium Non-equilibrium Solar cell operating principles Solar cell: • Absorber layer • Semi-permeable membranes Χe electron affinity absorber 0 -q ψ χe E C E F E V Solar cell oper