Single-layer polymer device

MIM or SIM [82-84] diodes to the PPV/A1 interface provides a good qualitative understanding of the device operation in terms of Schottky diodes for high impurity densities (typically 2> 1017 cm-3) and rigid band diodes for low impurity densities (typically<1017 cm-3). Figure 15-14a and b schematically show the two models for the different impurity concentrations. However, these models do not allow a quantitative description of the open circuit voltage or the spectral resolved photocurrent spectrum. The transport properties of single-layer polymer diodes with asymmetric metal electrodes are well described by the double-carrier current flow equation (Eq. (15.4)) where the holes show a field dependent mobility and the electrons of the holes show a temperature-dependent trap distribution. 

X Yang, D Neher, D Hertel, and TK Daubler, Highly efficient single-layer polymer electrophosphorescent devices, Adv. Mater., 16 161-166, 2004. 

S Kan, X Liu, F Shen, J Zhang, Y Ma, Y Wang, and J Shen, Improved efficiency of single-layer polymer light-emitting devices with poly(vinylcarbazole) doubly doped with phosphorescent and fluorescent dyes as the emitting layer, Adv. Funct. Mater., 13 603-608, 2003. 

Figure 1-1. Schematic drawing of a single-layer electroluminescent device. An applied electric field leads to injection of holes (positive charges the majortiy charge carriers in polymers such as PPV) and electrons (usually the minority charge carriers) into the light-emitting polymer film from the two electrode contacts. Formation of an electron-hole pair within the polymer may then result in the emission of a photon. Since holes migrate much more easily through PPV than electrons, electron-hole recombination takes place in the vicinity of the cathode.

FIGURE 5.27 Schematic structure of a single-layer polymer LED device formed with polyfp-phenylene vinylene). (After Burroughes, J. H., Bradley, D. D. C, Brown, A R., Marks, R. N, Mackay, K., Friend, R. H., Bum, R L., and Holmes, A. B. 1990. Nature, 347, 539.)... 

Figure 3a. Comparison of efficiency-current characteristics for the EL device rrO/PPV/polymer PMA-PPD lOa/Ca with those for the single layer reference device...

Anthracene Groups. A homopolymer from 9-(4-vinylphenyl)anthracene emits green light originating from the excimer of the anthracene units. Ruores-cent vinyl polymers containing 9-phenylanthracene pendants were synthesized and examined as an emitter layer in organic electroluminescent devices. The single-layer polymer EL device uses the homopolymer. 

Figure 6.1 Four device architectures of conjugated polymer-based photovoltaic cells (a) single-layer polymer PV cell (b) bilayer polymer PV cell (c) disordered bulk heterojunction (d) ordered...

Fig. 178. Device structure of a single-layer polymer electroluminescence diode.

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