Interface energy diagram

FIGURE 3.3 Schematic of an organic-metal interface energy diagram (a) without and (b) with an interface dipole and (c) UPS spectra of metal and organic. (From Hung, L.S. and Chen, C.H., Mater. Sci. Eng., R39, 143, 2002. With permission.)... 

Figure 4.22. Schematic of an organic semiconductor/metal interface energy diagram (a) A = 0 and (b) A 0.

Figure 12. Energy diagram of a semiconductor/electrolyte interface showing photogeneration and loss mechanisms (via surface recombination and interfacial charge transfer for minority charge carriers). The surface concentration of minority...

Figure 29.4 shows an example, the energy diagram of a cell where n-type cadmium sulfide CdS is used as a photoanode, a metal that is corrosion resistant and catalytically active is used as the (dark) cathode, and an alkaline solution with S and S2 ions between which the redox equilibrium S + 2e 2S exists is used as the electrolyte. In this system, equilibrium is practically established, not only at the metal-solution interface but also at the semiconductor-solution interface. Hence, in the dark, the electrochemical potentials of the electrons in all three phases are identical. 

Hyper-Raman spectroscopy is not a surface-specific technique while SFG vibrational spectroscopy can selectively probe surfaces and interfaces, although both methods are based on the second-order nonlinear process. The vibrational SFG is a combination process of IR absorption and Raman scattering and, hence, only accessible to IR/Raman-active modes, which appear only in non-centrosymmetric molecules. Conversely, the hyper-Raman process does not require such broken centrosymmetry. Energy diagrams for IR, Raman, hyper-Raman, and vibrational SFG processes are summarized in Figure 5.17. 

Fig. 15. Schematic energy diagram of the n-type semiconductor electronic bands at the solid/liquid interface modulated by discontinuous metal coating ...

Fig. 4-11. Energy diagram for electron transfer from a standard gaseous electron across a solution/vacuum interface, through an electrolyte solution, and across a metal/solution interface into a metal electrode = real potential of electrons e,s) in electrolyte...

Fig. 10-3. Energy diagrams for an n-type semiconductor electrode (a) in the daik and (b) in a photoexdted state S = aqueous solution = conduction band edge level at an interface cy = valence band edge level at an interface = Fermi level of oxygen...

Fig. 10-26. Energy diagram for a cell of photoelectrolytic decomposition of water consisting of a platinum cathode and an n-type semiconductor anode of strontium titanate of which the Fermi level at the flat band potential is higher than the Fermi level of hydrogen redox reaction (snao > epM+zHj) ) he = electron energy level referred to the normal hydrogen electrode ri = anodic overvoltage (positive) of hole transfer across an n-type anode interface t = cathodic overvoltage (negative) of electron transfer across a metallic cathode interface.

Fig. 3.9 Energy diagram of the semiconductor-electrolyte interface under equilibrium, (a) The Fermi level Ep is equal to redox potential energy, Ep, redox (b) The Fermi level, Ep is equal to reference electrode energy, Ereference- (c) Potential disMbution. (d) Charge across the interface.

Fig. 5. Energy diagram of a semiconductor-electrolyte interface (a) with no external voltage (b) and (c) under the application of an external voltage. The diagram explains the pinning at the semiconductor electrode surface of the energy band edges [transition from (a) to (b)] or of the Fermi level [transition from (a) to (c)].

Fig. 16. Energy diagram of a semiconductor (n-type)-electrolyte interface (a) in darkness, (b) under illumination.

Fig. 31. Energy diagram of a semiconductor-electrolyte interface under photoemission. The potential energy of the delocalized electron in the solution dtloc is taken as the origin.

In the case of redox electrodes, the ease with which electrons can tunnel through a potential barrier of the type present at an electrode interface makes the use of classical activated complex theory (with the electrons as one reactant) inappropriate. In Fig. 2.11(a) an electron energy diagram of a redox electrode at equilibrium is shown. For an electron transfer between the phases to be successful, it is necessary for the acceptor or donor in solution to have an energy level exactly equal to a complementary level in the metal. In the equilibrium situation it is seen that there is an equal chance of transfer of an electron from a filled metal level to an unoccupied... 

In an isolated electrode, the VB, the GB and the Fermi level all have constant values throughout the depth of the electrode. If it is immersed in an electrolyte there will be a movement of charge at the interface so that the Fermi level coincides with the redox level of the species contained in the electrolyte. This is somewhat similar to the equalization of the levels of two liquids in contact, the equilibrium condition being that the pressures should be equal at the point of contact. In an energy diagram this is shown as a... 

Figure 4.68 Energy diagram of the valence and conduction bands of a semiconductor-electrolyte interface. The bending of the bands corresponds to the effect of the electric field...

Figure 11. Energy diagram of the interface between n-GaP and an electrolyte...

Figure 1. Combined energy diagram for a regenerative photoelectrochemical cell with n-CdSe as the anode, metallic cathode and polysulfide as the electrolyte. The diagram indicates some of the charge accumulation modes that might contribute to the potential distribution at the interface. ((Qn) ionized donors (Qdt) deep traps ...

Figure 4. Energy diagram of a Schottky barrier formed at an n-type semiconductor-electrolyte interface...

In the chapter on device motivation to the study of polymer surfaces and interfaces, a diagram similar to Fig. 8.3 appears. At first glance, there is an apparent discrepancy between the UPS model of Fig. 8.2 (bottom), and LED mode 2>26, in Fig. 8.3. If a second metal, with workfunction less than that of the metal shown in Fig. 8.2, is used as the counter electrode on the polymer film in the UPS model, assuming the direct alignment of the various energy band edges, the level must move, such that Ajt = 0 throughout the sandwich, upon... 

Fig. 24. Energy diagram of the boron-doped diamond/aqueous redox electrolyte solution interface (a) at the flat-band potential (b) at the equilibrium potential of Fe(CN)63, 4 system. Ec is the energy of conduction band bottom, Ev is the energy of valence band top, F is the Fermi level, Eft, is the flat-band potential. Shown are the electrochemical potential levels of the Fe(CN)63, 4 and quinone/hydroquinone (Q/H2Q) systems in solution. The electrode potential axis E is related to the standard hydrogen electrode (SHE). Reprinted from [110]. Copyright (1997), with permission from Elsevier Science.

Fig. 4. Energy diagram of the Ti02-electrolyte interface in basic medium. The Ti02 energy levels at pHO are included in order to show the change in overlapping of the surface states (S.S.) with 02 empty levels.

Fig. 1 Schematic energy diagram of the semiconductor/adsorbate interface for different experimental conditions.

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