HOMO energy level

Fig. 8 Structure-photophysical properties relationship of fluorescein derivatives. Measured in 0.1 N NaOH(aq). bOxidation potential of corresponding benzene moiety, obtained in acetonitrile containing 0.1 M TBAP. °HOMO energy level of the corresponding benzene moiety, calculated with B3LYP/6-31G(d)//B3LYP/6-31G(d) by Gaussian 98 W...

A new branched carbazole derivative with phenyl ethylene moieties attached, l,3,5-tris(2-(9-ethylcarbazyl-3)ethylene)benzene (TECEB, 41) (Scheme 3.15), was prepared as a HTM for OLEDs [86], TECEB has a HOMO energy level of —5.2 eV and hole-drift mobility of 1(T 4 cm2/(V s), comparable to NPD. The device performance (maximum luminance of about 10,000 cd/m2 and current efficiency of 3.27 cd/A) in a standard HTL/tris-(8-hydroxyquino-line) aluminum double-layer device is also comparable to NPD, but TECEB has a higher Tg (130°C) and its ease of synthesis is superior to NPD. Distyryl units linked to a TPD derivative, A, A"-bis(4-(2,2-diphenylethenyl)-phenyl)-jY,jV -di(p-tolyl)-bendidine (DPS, 42) (Scheme 3.15), reported by Yamashita and coworkers, showed good hole transport properties and improved thermal stability compared with the parent TPD [87]. 

HOMO energy level of the polymer is 5.32 eV. It was demonstrated that the EL performance of super yellow PPV and blue polyfluorene derivatives using this hole transport polymer is comparable to or better than that using PEDOT PSS as a HTL [102],... 

HOMO energy level matching the HTL to facilitate hole transport... 

Alkynes add to azides to form 1,2,3-triazoles (equation 10). In contrast to the azide additions to alkenes, the regioselectivity with alkynes is low and usually mixtures of triazoles are formed.178 Alkynes have HOMO energy levels lower than those of the corresponding alkenes, although the LUMOs are ap-... 

Table 12 shows oxidation potentials ( 1/2) of a series of permethylpolysilanes determined by a.c. polarography or cyclic voltammetry50,51. The 1/2 values decrease as the chain length increases. This reflects the HOMO energy levels of these permethylpolysilanes52. 

Figure 3. Comparison of the LUMO energy levels for a series of conjugated unsaturated organic molecules and HOMO energy levels for Sn2-. C - vinyl or phenyl Z = electron withdrawing group such as -CHO, -CN etc. (adapted from LaLonde et al. 1987) (29).

Pentacene ethers 37-39 (Fig. 3.8) were prepared in an attempt to reduce the HOMO energy level relative to functionalized pentacene 29 [52]. These cyclic ether compounds were surprisingly stable, soluble and easily crystallized. Saturated diox-ane compound 37 has an oxidation potential of 0.580 V vs SCE (similar to that of unfunctionalized pentacene), but the axial hydrogen atoms on the dioxane ring prevent -stacking interactions in the crystal. Derivatives 38 and 39 were synthesized to overcome this structural issue. Although the change of oxidation potential... 

M = Tb, Lu) into organic thin-film transistors by LB technique and reported their field effect mobility, which represented the first report for p-type OFETs based on bis(phthalocyaninato) rare earth complexes prepared via LB method [88], Due to the highly ordered molecular arrangement of M(Pc)[Pc(OC8Hi7)g] (M = Tb, Lu) in LB films and the appropriate HOMO energy level of these double-deckers relative to the Au source-drain electrodes, the OFETs reported in that work exhibited higher hole transfer mobility of 1.7 x 10-3 cm2 V-1 s-1 in comparison with those fabricated from monomeric phthalocyanine LB films. 

The second characteristic center of reactivity within phosphaal-kenes is the (p-p)-n bond. The reactivity is more similar to the C=C than to the corresponding C=N or P=N double bond. This is in accordance with the highest occupied molecular orbital (HOMO) energy levels of the phosphaalkenes, which frequently are n orbitals, as with olefins (51). The olefinic character is also demonstrated by the lower polarity of the P—C bond in comparison with the C—N or P—N bond. 

HOMO energy level with respeot to the Fermi level. HOMO energy level with respeot to the vaouum level. Energy of the lowest-energy-loss feature. 

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