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Lecture 14 Current-Potential Curves at Semiconductor Electrodes Reference. 1. R. Memming, Semiconductor Electrochemistry, Wiley-VCH, 2000 (e-book) 2. A.J. Bard and L.R. Faulkner, Electrochemical Methods: Fundamentals and Applications, Wiley, 2001 3. J. O’M. Bockris, A.K.N. Reddy, and M. Gamboa-Aldeco, Modern Electrochemistry, Kluwer Academic/Plenum Publishers, 2000 Lecture note http://les.kaist.ac.kr/B_Lecture Recap: I-V Curves at Metal Electrodes Recap: Metal-Electrolyte Interface At equilibrium Under polarization Potential Controls Activation Energy Recap: Bias Changes the Fermi Level I-V Curves of Semiconductor Electrodes Band Bending of Semiconductor n-type Semiconductor-Electrolyte Interface 𝑜 𝑈𝑟𝑒𝑑𝑜𝑥 − 𝑈𝑟𝑒𝑑𝑜𝑥 = 𝑘𝑇 𝑐𝑜𝑥 ln( ) 𝑒 𝑐𝑟𝑒𝑑 The activation energy is independent of the relative concentration of the redox system and also independent of the externally applied voltage! Quantitative Derivation of Current-Potential Curves Conduction Band Processes jc+: an electron transfer rate associated from a filled state in a redox system to an empty state in a SC. jc-: an electron transfer rate associated from a filled state in a SC to an empty state in a redox system. Valence Band Processes jv+: an electron transfer rate associated from a filled state in a redox system to an empty state in a SC. with jv-: an electron transfer rate associated from a filled state in a SC to an empty state in a redox system. We will define another rate constants for each equations so that I-V Relationship At equilibrium Conduction band process I-V Curves of Semiconductor Electrodes Light-induced Process Next Meeting Current-Potential Curves at Semiconductor Electrodes: Part II