Conductive transparent layers

Thin solid films are layers that are present on a surface and have their top interface exposed to the environment Their extreme thinness in comparison with their lateral dimensions makes them systems that are infinite in two dimensions and are confined between an infinite gaseous phase and an infinite solid phase in the third one. As a result the global property of a layer is a combination of bulk and interface properties thus, one has to take into accoimt the thickness of the layer and the nature of the substrate when designing a coating for a specific application. Thin layers can be used for various purposes, depending on their surfece and/or bulk intrinsic properties. They can be dense, porous, patterned, multilayered, composite, and so on. Sol-gel films can be found in many different application domains such as optics (e.g., antireflection, self-cleaning, smart windows, and conductive transparent layers), electronics (e.g., microfabrication, low-/ , and self-assembled monolayers (SAMs)), protection (e.g., anticorrosion, anti-abrasion, and antistatic), and analysis (e.g., selective sensors). In most of these applications, the function must be identical on the whole surface of the substrate, and thus the thickness has to be controlled as much as possible and must be as uniform as possible. 

A typical vaponr deposited EL device consists of a glass snbstrate coated with a conducting transparent indinm tin oxide electrode, on top of which is a 100-500 A hole transport layer (HTL), followed by a thin (= 100 A) light emitting layer (EML), then a 100-500 A electron transport layer (ETL) and finally a cathode of an alloy such as Mg Ag. This is illustrated in Fignre 3.32. 

Polymer nanotubes composites are now extensively studied. Indeed, one may associate the properties of the polymer with those of nanotubes. This is the case of the mechanical reinforcement of standard polymer for example, but also one can take advantage of the specific electronic properties of the nanotubes. Therefore, we prepared composites with either saturated polymers like polymethylmethacrylate and MWNTs [27]. The electrical conductivity of these compounds as a function of the nanotube content exhibits for example a very low percolation threshold, (a few % in mass) and therefore they can be used as conducting and transparent layers in electronic devices such as Light Emitting Diodes (LEDs). Another type of composite that we have studied is based on the use of a conjugated polymer, polyphenylene-vinylene (PPV) known for its photoluminescence properties and SWNTs. We prepared this composite by mixing SWNTs to the precursor polymer of PPV. The conversion into PPV was subsequently performed by a thermal treatment at 300°C under dynamical vacuum [28],... 

Thin ZnO films can be used either as a transparent and conductive window layer, or as a buffer layer, within CuInS2 (CIS) and Cu(In,Ga)Se2 (CIGS) thin film solar cell devices (see Chaps. 4 and 9). In both cases, the ZnO layers... 

Transparent polymer solar cells (i.e., polymer solar cells with transparent electrodes) can be easily fabricated based on inverted architecture and have important application in tandem architectures as well. We can form transparent solar cells by replacing the Al top electrode with 12 nm Au in the inverted structure. The J-V curves for this transparent polymer solar cell, with light incident from ITO and Au side, are shown in Figure 11.17. The difference between the two J-V curves is due to the partial loss by the reflection and absorption at the semitransparent Au electrode. To provide sufficient electrical conductance, Au layer thickness has to be sufficient and the optical loss at Au electrode becomes significant. However, the inverted solar cell structure has the V2O5 layer which is not only transparent but also provides effective protection to the polymer layer. A transparent conductive oxides electrode, such as ITO, can therefore be deposited without compromising device performance. 

Low loss solid-state interfaces need to be engineered for bridging component cells in a multijunction device structure, for example, using tunnel junctions or intermediate transparent conductive oxides layers. 

The possibility of e-paper is a consequence of the development of thin transparent electronic circuitry based on conducting and semiconducting synthetic polymers. The development of these materials was recognized with the Nobel Prize in 2000. The Gyricon approach involves a thin, transparent layer of silicone rubber, impregnated with a high concentration of polyethylene spheres, typically 50-100 /um in diameter. Each sphere is black on one side and white on the other in addition, the black... 

A boron nitride film is applied between the transparent conductive SnOg layer and the amorphous silicon layer in photoelectric solar cells, thus preventing Sn and O diffusion [101]. 

Fig. 6. Schematic operation of a twisted nematic cell for (a) no voltage and (b) a voltage several times the threshold (14) applied across the nematic layer. The cell components are as follows (1) and (2), polarizer and analyser respectively with their polarization directions orthogonal as indicated by the dark arrows (3) glass substrates (4), conducting transparent electrodes and (5), alignment layers with the rubbing directions orthogonal between the upper and lower substrates.

The low oxidation (p-doping) potential of poly(oxythiophene)s along with high conductivity, transparency and stability of doped state make them ideal as a transparent conductor and as a hole-transport layer in various optoelectronic devices. On the other hand, alkyl-substituted EDOT and ProDOT derivatives are suitable for electrochromic applications. However, PEDOT remains one of the most extensively studied polymers in this class due to the easy commercial access of EDOT monomer and processable PEDOT polymers (Clevios-P). 

Glass or plastic substrate Electronically conductive transparent tiim Primary electroch ramie palymer Ion conducting layer (electrolyte)... 

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