Charge carrier mobility, polymer

Two main methods have been used to measure the charge carrier mobility in electroluminescent polymers time of flight (TOF) carrier transit time measurements and analysis of the current-voltage (1-V) characteristics of single carrier devices in the space charge-limited current (SCLC) regime. A summary of the results for the hole mobility of PPV and PPV-related polymers is given in Table 11-1 [24, 27-32]. For... 

As expected, the coordination of Pt markedly influences the photophysical characteristics of the PPE. The photoluminescence is efficiently quenched, and the absorption maximum in the visible regime experiences a hypsochromic shift. The charge-carrier mobility of different EHO-OPPE-Pt samples was determined by TOE measurements as described above for the neat EHO-OPPE. The shape of the photocurrent transients of all EHO-OPPE-Pt samples was similar to those shown in Figs. 6 and 7 for the neat EHO-OPPE. This indicates that these organometallic conjugated polymers networks are also characterized... 

Fig. 13 Experimental (symbols) and theoretical (lines) data for the current-density as a function of applied voltage for a polymer film of a derivative of PPV under the condition of space-charge-limited current flow. Full curves are the solution of a transport equation that includes DOS filling (see text), dashed lines show the prediction of Child s law for space-charge-limited current flow assuming a constant charge carrier mobility. From [96] with permission. Copyright (2005) by the American Institute of Physics...

Pasveer WE, Cottaar J, Tanase C, Coehoom R, Bobbert PA, Blom PWM, de Leeuw DM, Michels MAT (2005) Unified description of charge-carrier mobilities in disordered semiconducting polymers. Phys Rev Lett 94 206601... 

The synthesis, characterization, electrical conductivity, and field effect mobility of a series of novel soluble N-alkyl dithieno[3,2-b 2, 3 -d]pyrrole (DTP) and thiophene (TH)-based copolymers (DTP-co-THs) were reported (06MM1771 08JA13167). The incorporation of DTP units extends n conjugation, and the introduction of thiophene subunits imparts good solubility, high conductivity, and high charge carrier mobility. Therefore, the incorporation of DTP units and various substituted thiophenes into the polymer backbone affords the ability to enhance the solubility, lower the band gap, and achieve the enhanced electronic properties. 

Stable polythiophene semiconductors 237 incorporating the thieno[2,3-fc]thiophene ring system were synthesized by Stille coupling of 5,5 -dibromo-4,4 -dialkyl-2,2 -bithiophene 235 with thieno[2,3-fc]thiophene-2,5-diylbis(trimethystannane) 236 (Scheme 48). The polymers 237 described showed both good charge carrier mobility and stability to ambient air and light [62],... 

The use of transition or rare earth metal complexes as emitting materials for OLED has attracted much attention recently because of the enhancement in EL efficiency from triplet excited state.16 Chan and co-workers demonstrated that incorporation of ruthenium bipyridyl complexes into conjugated polymers would enhance the charge carrier mobilities.17 Through attachment of different transition metal complexes onto polymer chains, tuning of light-emitting properties could be achieved.18... 

A large number of carriers remain within the sample for more than two or three times the transit time of the fastest carriers. A smaller fraction remain within the sample for considerably longer times. In addition the charge carrier mobility in amorphous polymer systems increases with the applied electric field whereas in crystalline materials it remains invariant. 

In the previous section on the short-circuit current, it was demonstrated theoretically and experimentally that Isc in conjugated polymer-fullerene solar cells is controlled to a considerable extent by mobility of the majority charge carriers in the cell s active layer [158]. Moreover, activated behavior of charge carrier mobility in conjugated polymers is known to result in higher mobility at higher temperatures (for a review, see [159]). Accordingly,... 

Fig. 9.34 Correlation of electrical conductivity and charge carrier mobility for a doped conjugated polymer thermally dedoped device and o separately doped devices. The fits, thick and thin lines, are described in the text. Reproduced with permission of the American Institute of Physics from Jamett et al. (1995).

The optoelectronic properties of conjugated polymers containing the rhenium diimine unit [Re(CO)3(phen)Cl] have been studied. Charge-carrier mobility measurements showed that the presence of metal complexes could facilitate the charge-transport process, and the enhancement in carrier mobility was dependent on the metal content in the polymer. The use of transition metal complexes for both photovoltaic and electroluminescence applications was demonstrated. 

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