Solution-processed materials

There is a range of difficult technological and scientific hurdles that will need to be overcome before reliable products can be manufactured with the required performance at low cost by commercial printing techniques. A complete set of solution processible materials including not only conductors, semiconductors and di-... 

In addition to vacuum-deposited small-molecule structures, bilayer devices have been fabricated from conjugated polymers and other solution-processible materials. One study reports a 1.9% efficient device fabricated by lamination of two spin-coated polymer layers (Granstrom et al, 1998). In principle, polymer bilayers can also be fabricated by spin-coating of successive layers using incompatible solvents. A more practical route to planar bilayers is the deposition of successive layers that have previously been spin-coated and removed from the substrate by a float-off technique (Ramsdale et al, 2002). 

More generally for the manufacturing sector flexible is synonymous of rollable , thus the development of deposition techniques fully compatible with plastic substrates, low temperature processes and solution processable materials, and suitable for flexible substrates for roll-to-roll manufacturing technologies is mandatory. 

Technical issues in printed electrodes were briefly reviewed for all-printed TFT applications. Surface morphology and edge waviness of the printed electrode should be well controlled to produce uniform and stable TFT behavior and consistent thin-film device performances. This investigation fabricated solution-process TIPS-pentacene based TFT with the printed silver electrodes. Solution-process materials can be readily combined with a low-cost printing process, which can significantly reduce complexity in the fabrication and manufacturing process. In addition, these types of solution-process TFT can be fabricated at low temperatures and they can be also readily implemented on plastic substrates for flexible electronics applications. 

When two or more components are present in a thin film, there is the potential for phase separation and therefore a wide range of microstructural variation. In addition, for solution-processed materials, the solvent acts as a further component that is controllably removed during fabrication. Therefore, in the case of small-mole-cule/polymer systems, there can be several factors that determine the overall phase behavior first, the thermodynamics of mixing between components and the balance of entropic and enthalpic contributions to the free energy of mixing, AG ixi second, the interaction between solution and substrate or atmosphere interfaces and finally, the kinetics of solvent evaporation and changes to the solution that this induces, such as viscosity variation or phase separation within the solution. It should be noted that these processes are often far from thermodynamic equilibrium leading to a film microstructure that can sometimes be difficult to predict. 

The attachment of hexyl-capped quaterthiophenes to a carbosilane core via longer alkyl side-chains was achieved by hydrosilylation reactions. JCirchmeyer et al. obtained quaterthiophene-fiinctionalized tetrahedral structure 5.51 (Chart 1.73), which were highly soluble in organic solvents. In OFETs these solution-processable materials showed excellent charge carrier mobility values of 10 cm V s and on/off-ratios of 10 . Because of the high proportion of saturated parts in the core, this result is... 

PVP or poly(vinyl phenol) is a polymer dielectric. The advantage of using a polymer dielectric over an inorganic one is the ability to formulate a process which completely relies on solution processible materials. This process can potentially be... 

In 1976, TBI patented a solid-state reference electrode shown in Figure 4-3b that is nearly impervious to process contamination. The reference consists of four wooden dowels saturated with potassium chloride solution. Process material must work its way up into the innermost wooden dowel, where the internal silver-silver chloride element resides to create a drastic offset in the pH reading. Teflon is substituted for the... 

The metal oxide based CTLs (including ETLs and HTLs) play an important role in overall device performance for bulk-heterojunction OSCs. In this chapter, I have explained the functions and effects of the CTLs and have focused on CLTs using solution-processible materials in organic optoelectronic devices. Examples of different solution process methods of CTLs were presented. For various ETL and HTL materials, performance comparisons of each solution process method were discussed. By doping and introduction of metal NTs, the electrical properties of CTLs can be further improved by different concepts such as plasmonic-electrical effects, carrier accumulation, etc. 

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