Lowest unoccupied molecular orbital Fermi level

In Eq. (1), / is the maximum current that can run through the cell. The open circuit voltage (V ) depends on the highest occupied molecular orbital (homo)level of the donor (p-type semiconductor quasi Fermi level) and the lowest unoccupied molecular orbital(lumo) level of the acceptor (w-type semiconductor quasi Fermi level), linearly. P in is the incident light power density. FF, the fill-factor, is calculated by dividing P by the multiplication of / and V and this can be explained by the following Eq. (2) ... 

Fig. 9 OMT bands for NiOEP, associated with transient reduction (1.78 V) and transient oxidation (—1.18 V). Data obtained from a single molecule in a UHV STM. The ultraviolet photoelectron spectrum is also shown, with the energy origin shifted (by the work function of the sample, as discussed in [25]) in order to allow direct comparison. The highest occupied molecular orbital, n, and the lowest unoccupied molecular orbital, %, are shown at their correct energy, relative to the Fermi level of the substrate. As in previous diagrams,

If the electrodes match the lowest unoccupied molecular orbital (LUMO) of the acceptor and the highest occupied (HOMO) level of the donor, respectively, the contacts can be regarded as ohmic. The maximum Voc for this case is schematically indicated by yoci in Fig. 5.13 and is thus controlled by the bulk active layer material properties. Non-ohmic contacts, as shown in Fig. 5.13, a Voc with magnitude V0c2 should be observed, according to the MIM model. However if the Fermi level of the contact metal is pinned at the LUMO and of the anode with the HOMO, the observed F0c by the properties of the acceptor and the donor and will become insensitive to the work function difference of the electrodes. 

The Seebeck coefficient oc relates to the energy gap between the Fermi level, EF (or highest occupied molecular orbital) and the impurity level E (or lowest unoccupied molecular orbital) as shown in the following equation ... 

The AR mechanism for rectification [121], showing a proposed D-molecule electron flow from the excited zwitterion state D+-ground state D°-metal electrodes M-, and M2. Here = 0 is the vacuum level, (j> is the work function of the metal electrodes, V is the potential applied on the left electrode (the right electrode is grounded), lD is the ionization potential of the donor moiety D, Aa is the electron affinity of the acceptor moiety A, and fF1 and F2 are the Fermi levels of the metal electrodes. HOMO (LUMO) levels are the highest occupied (lowest unoccupied) molecular orbitals of D-tr-A. 

An important issue for the performance of an organic electronic device like an OFET is the injection of charge carriers, electrons or holes, from the electrode into the organic material. In case of the commonly used metal electrodes an efficient electron injection is possible only if the Fermi level of the metal and the energy of the lowest unoccupied molecular orbital (LUMO) of the organic material differs by a small amount only. A similar statement applies for hole injection, in this case the position of the highest occupied molecular orbital (HOMO) has to match with the position of the Fermi level. When noble metals, in particular Au, are being used for an electrode one may naively assume... 

In considering the electronic properties of crystalline solids, one need only be concerned with the energy states near the Fermi level, since these are the states that affect the physical properties of the solid. In the organic charge-transfer salts we will be discussing, these states are derived from the Highest Occupied Molecular Orbitals (HOMOs) of the donor molecules, and Lowest Unoccupied Molecular Orbitals (LUMOs) of the acceptor molecules. 

It is important to note that many metallic properties, such as the Knight shift and the Korringa relationship, are determined by the finite and quasiFermi level local density of states ( p-LDOS). In the approximation most familiar to chemists, what this means is that the highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) gap in metals is much smaller than the thermal energy kf,T, and the value of the / f-LDOS reflects the frontier orbital contributions in a metallic system [23]. The /ip-LDOS also represents a crucial metal sxudace attribute that can serve as an important conceptual bridge between the delocalized band structure (physics) picture and the localized chemical bonding (chemical) picture of metal-adsorbate interactions. 

The two electrode materials are in direct contact with the liquid electrolyte, an environment made up of molecular species, characterized by their highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels. Adding an electron to the electrolyte s LUMO results in the reduction of the latter, whereas removing an electron from its HOMO results in its oxidation. So long as the positive electrode material s Fermi level is situated above the electroljde s HOMO level, no electron transfer will occur from the electrolyte to the positive electrode, and the electrolyte remains electrochemically stable since it does not oxidize continually on contact with the electrode. This remains theoretically true for positive electrode materials whose potential does not exceed approximately 4.5 V versus Li /Li, which is the case for the usual materials, such as LiCo02. 

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