Optical absorption and photoluminescence spectra

Figure 2. Optical absorption and photoluminescence spectra of thin films (a) POBTPQ and MEH-PPV (b) P4HQ and P40Q.

Figure 17.2 (A) Absorption and photoluminescence spectra of CdSe quantum dots prepared from CdO, CdC03, and Cd(AcO)2 in the presence of different ligands. (B) Increase in the optical density (at 400 nm) of a CdSe quantum dot reaction mixture with time under reaction at 75 "C. Color pictures in the inset of B represent CdSe (a,b) andCdSe-ZnS (c) quantum...

UV/Vis absorption and photoluminescence spectra of semiconductors 368-373 were measured in solution to assess the effect of carbonyl functionalization on the optical absorption/emission spectra and resultant optical HOMO-LUMO energy gaps (Egap) (07CM4864). 

The skeleton-side-chain interaction is reflected in optical properties. The absorption and photoluminescence spectra of poly(methylpropylsilane) and poly(methylphenylsilane) are shown in Figure 14. For poly-(methylpropylsilane), the spectrum profiles are explained by the simple band model just discussed. However, for poly(methylphenylpolysilane), the spectrum profiles are very different. The absorption peak at 3.7 eV corresponds to a a-a transition, and the second peak at 4.5 eV corresponds to a tt-tt transition in phenyl side chains. The sharp photoluminescence peak originates from the a -CT transition. 

The substituted five-ring OPVs have been processed into polycrystalline thin films by vacuum deposition onto a substrate from the vapor phase. Optical absorption and photoluminescence of the films are significantly different from dilute solution spectra, which indicates that intermolecular interactions play an important role in the solid-state spectra. The molecular orientation and crystal domain size can be increased by thermal aimealing of the films. This control of the microstructure is essential for the use of such films in photonic devices. 

The absorption and photoluminescence spectra of both materials are shown in Fig. 12.7 (c,d). The luminescence of p-scxiphcnyl is very similar to the spectrum of the spiro-derivative, only the vibronic sidebands are more pronounced. This shows that aside from the improved morphological stability, the spiro-linkage merely leaves the optical properties of the chromophore unaltered. 

All publications on mesoporous soHds with nanoparticles discussing optical properties can be generally divided into two large groups. The first group consists of works on different kinds of semiconductor particles (metal sulfides, selenides, oxides, etc.) where such particles are obtained in mesoporous solids and their UV-visible absorption and photoluminescence spectra are recorded. As a rule, these papers state the change of optical properties of nanoparticles compared to bulk, similar to semiconductor nanoparticles prepared in any... 

The formed colloidal solutions with nanoparticles were characterized by optical absorption and photoluminescence spectroscopy for monitoring the changes in the plasmon absorption characteristics and luminescence properties, transmission electron microscopy (TEM) and X-ray diffraction (XRD) in order to analyze the final size and structure of nanoparticles. The absorption spectra of the colloids were recorded with a UV-visible spectrophotometer (CARY 500) using a 1-cm-pathlength-quartz cell for the absorption measurements. 

Fig. 10 Optical absorption and photoluminescence PL) spectra of the uncapped and PVP-capped ZnO nanoparticles. Reprinted with permission from [221]. Copyright 2000 American Physical Society...

The optical absorption and emission spectra of conjugated polymers and oligomers have been reviewed. The optical bandgaps of the conjugated polymers that are organic semiconductors range from 1 to 3.5 eV. The photoluminescence spectra of conjugated... 

Since there is no principle difference between an ion and an optically excited yet neutral molecule embedded within a polarizable medium, the disorder concept applies to optical transition to molecular chromophores as well. In fact, the observation of inhomogeneously broadened absorption and photoluminescence spectra is a direct and simple experimental probe of the DOS distribution [14]. For this reason time resolved photoluminescence is a useful analogous tool for checking the validity of concepts for analyzing charge transport in random organics. 

The absorption and photoluminescence (PL) spectra of a-6T measured at 80 K are shown in Figure 7-24. There is an onset of absorption at 2.1 eV, with several sharp peaks and a maximum at 2.8 eV. A second absorption band is seen at 4.5 eV and is due to direct excitation of the thiophene ring. We take the first peak as the 0-0 transition and calculate an optical gap j,=2.4eV. The PL spec-... 

Fig. 19 (a) Optical absorption and (b) photoluminescence spectra of CdSe and CdSe QDs capped with different concentration of cytosine. Sample A is as-prepared QDs and Samples B and C are capped QDs. (Adapted from [75])... 

The spectra of optical absorption and cw-photoluminescence (PL) are typical for small semiconductor nanoparticles under a strong quantum confinement effect. 

FIGURE 22.25 Room temperature optical spectra of PDPA- Bu film absorption, a (in terms of optical density) and photoluminescence (PL). The polymer repeat unit is shown in the inset. (From Korovyanko, O.J., et al., Phys. Rev. B, 67, 035114, 2003. With permission.)... 

The optical properties of polymers 27 and 31, as well as compounds 28 and 32, were compared. UV-vis absorption specha and photoluminescence spectra are shown in Fig. 11, and the data are summarized in Table 1. The A , of 27 and 31 were observed at 380 and 436 nm, respectively, which were redshifted in comparison with those of 28 (X =310 nm) and 32 (2max=413 nm), as a result of the through-space conjugation among the stacked Jt-electron systems. 

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