Solution-processable polymers

Monochrome AMPLEDs Made with Solution-Processible Polymers.29... 

Solution-processible polymers with large band gaps and relatively high triplet energies may also be suitable for use as host materials. Examples of these include polyalkylfluorene (POF, 126), polyvinylene cabazole (PVK, 127), and rigid polycarbazoles (e.g., PCOX, 128) (Scheme 3.39). They can be used as host materials for a wide range of colors. Details will be described in Chapter 4. 

Following the encouraging results demonstrated by metal complex-based phosphorescent OLEDs [5,6,26], several groups started investigating a possibility to attain electrophosphorescence in solution-processible polymer-based LEDs. The first report on using... 

Zhang Y, de Boer B, Blom PWM (2009) Controllable molecular doping and charge transport in solution-processed polymer semiconducting layers. Adv Funct Mater 19 1901... 

In contrast to the small molecules, polymers can be processed easily from solution and therefore are useful for applications on flexible plastic substrates and in multilayer device configurations. However, solution-processed polymer films are inherently more disordered than in case of molecular FETs. It can be concluded from the above results that conjugated polymer based FETs are much cheaper than Si based device. However, the slow response and limited lifetime of the device restrict them to replace current Si technology. Nevertheless, the possibility of making flexible and flat panel with conjugated polymers open a new area of large-area low-cost plastic electronics [10]. 

Li G., Shrotriya V., Huang J., Yao Y., Moriarty T., Emery K. and Yang Y., High-efficiency solution processable polymer photovoltaic cells by self-organization of polymer blends . Nature Materials 4, 864—868. 

Fig. 11.24 Chemical structure of solution-processible polymers with iridium units covalently attached to oligofluorene segments [90],...

Wang, J.Z., Chang, J.F., and Sirringhaus, H., Contact effects of solution-processed polymer electrodes Limited conductivity and interfacial doping, Appl. Phys. Lett., 87, 083503, 2005. 

Understanding the crystal growth mechanisms of these solution-processable polymers is required to control the self-assembled structure during film formation. Most studies on solution-deposited semiconducting polymer thin films for OTFTs pertain to PATs [6,10,15,23,24,27,30,35,36,44,46-48,51-81]. The key factors affecting self-assembly of these polymers during solution processing are as follows ... 

A variation of MIMIC for patterning polymer semicondnctor TFT arrays was recently reported by Salleo and coworkers [105]. This techniqne exploits capillary forces to pattern a solution-processable polymer semicondnctor. In this method, the polymer semiconductor solution is spin-coated onto a snbstrate. A chemically treated PDMS stamp is then placed directly on top of the substrate coated with the polymer semiconductor solution. In the regions of contact, the PDMS stamp absorbs the solvent, leaving behind a solid polymer semiconductor film between the stamp and the substrate. In the recessed regions of the PDMS stamp, the polymer semiconductor solution wicks into the stamp due to capillary forces, effectively leaving behind a clean snrface in the noncontact regions. 

To improve the limit-of-detection, we replaced the 16 mm vacuum deposited CuPc/Cgg bilayer devices with 1 mm solution-processed polymer devices based on 1 1 blends by weight of poly(3-hexylthiophene) [P3HT] and [6, 6]-phenyl-C61-butyric acid-methylester [PCBM] - a soluble derivative of Ceo- The P3HT PCBM devices fabricated in our laboratory typically have very low short-circuit dark current densities of <10 mA cm , and are consequently a good choice for high sensitivity detection [21]. The... 

G. Li, V. Shrotriya, J. Huang, Y. Yao, T. Moriarty, K. Emery, Y. Yang, High-EfRciency Solution Processable Polymer Photovoltaic Cells by Self-Organization of Polymer Blends. Nat. Mater 2005,4,864-868. 

R. Zhou, R. Stalder, D. Xie, W. Cao, Y. Zheng, Y. Yang, M. Plaisant, P. H. Holloway, K. S. Schanze, J. R. Reynolds, et al. Enhancing the Efficiency of Solution-Processed Polymer Colloidal Nanocrystal Hybrid Photovoltaic Cells Using Ethanedithiol Treatment. ACS Nano 2013,7,4846-4854. 

V.S. Gevaerts, et al. Solution processed polymer tandem solar cell using efficient small and wide bandgap polymer fullerene blends. Advanced Materials, 2012 p. 1-5. 

Ong et al. have synthesized solution-processable alkyl-substituted poly(ter- and quarterthiophenes) 203-205 [369-371] and realized OFETs with hole mobilities up to0.14cm V s and on/off ratio over 10 in the case of203 [369]. Similar results have been reported by others [372]. Another approach consists in limiting rr-electron delocalization by incorporation of building block, such as thieno[2,3-b]thiophene that interrupts the conjugated pathway in the chain. The solution-processable polymers 206 leads to OFETs with hole mobility of 0.12-0.15 cm V s [373]. 

To summarize, almost 20 years after the first examples of PT-based OFETs [363,364,403], significant improvement of charge carrier mobility has been achieved from solution-processable polymers, thanks to the combination of technological optimization of the devices and progress in the design of materials combining better structural regularity, improved proccessability, and air-stability. 

Due to the easy processing, thin films of solution processable polymer-small molecule composites are more appealing for the realization of integrated circuits on large area by printing techniques. As for the coevaporated systems, the composition and microstructure of the film will affect the performances of the devices. For the polymer-small molecule blends, these characteristics can be tuned by the choice of solvents and spin coating parameters [52], until the optimal conditions are reached for balanced bipolar transport. 

Solution-processable polymers are more desirable than single-molecule systems since cheap and high-scale deposition methods, such as inkjet printing, can be used in place of vacuum deposition techniques. Soluble copolymers of thieno[3,2-( ]thiophene and thiophene have been obtained using the strategy... 

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