Drop-casting method

HKUST-1) IPA better results than drop-casting method Bahreyni (2012)... 

Under the right concentrations, polymer colloids can self-assemble to form close-packed hexagonal films. Simple drop-casting methods enable the formation of large arrays of hexagonally packed particles, which provide a very simple but effective template through which to deposit materials to form patterns. The interstices between colloidal particles are small, approximately triangular holes. 

Figure 16.14 Schematic illusttatioD of the drop casting method (left) before and (right) after evaporation.

Recently, a modified drop casting method for FET fabrication was reported. In this method, the Si/Si02 wafer was modified with a monolayer of aminosilane, a chemical known for its affinity to the CNTs, by treating with aminopropyltriethoxy silane (APTES) followed by assembly of SWNTs from a dilute solution of SWNTs. This method resulted in uniformly distributed high-density SWNT network when compared to surface without APTES (Eig. 14.2d). The process enables a wafer-level fabrication that can be used on both pre- and post-patterned electrodes and possesses flexibility with regard to controlling SWNT density in the network by manipulating SWNT concentration and deposition time. 

Perhaps the most simple way of obtaining small single crystals, albeit in an uncontrolled way, is the drop casting teclmique. This method consists in the deposition of a drop of a saturated solution of a soluble material on a clean substrate prior to the evaporation of the solvent in air, usually at RT. Some interesting examples are shown next. 

The simple drop casting crystallization method, discussed in Section 3.1, has also shown its validity in the determination of hole mobilities at least for the TTF-derivatives DTTTF (Mas-Torrent et al, 2004), EDT-TTF-(CONHMe)2 (Colin et al, 2004) and DBTTE (Mas-Torrent et al, 2005). In all cases, 1 cm s In this case the formation of high-quality organic/insulating interfaces is a matter of serendipity (see the discussion on the formation of nanovolcanoes at the surfaces of drop-cast single crystals in Section 3.1). 

Several polymer/polyelectrolyte-nanocrystal hybrid devices have been fabricated seeking to exploit the electro and photoluminescent properties of such material [179-188]. Device fabrication in all these cases is by low-cost self-assembly based techniques. These devices utilize thin films of these hybrids obtained either by multilayer deposition or drop/spin casting methods. Thus, solar cells have been made from poly(2-hexylthiophene)-CdSe nanorod multilayers, lasers from drop cast films of CdSe-titania composites and an infrared emitter from multilayers... 

For the characterization of the trap levels we applied the thermally stimulated current technique following the initial rise method [26] which was successfully applied to other conjugated polymers [27]. The device consisted of a sapphire substrate with an interdigital gold electrode structure on top of which a 200 nm thick polymer film was drop-cast. The gold electrodes had an overall length of... 

The oligothiophene films were prepared by solution cast methods and by vacuum deposition. Depending on the cast procedure, different layer thicknesses could be achieved. Preparation from solution either by drop casting or spincoating resulted in films ranging from 50 nm to 200 nm in thickness. Vacuum sublimation yielded very thin layers in the range of 10 nm to 15 nm, which nevertheless allowed to build-up and operate an OFET structure of molecular thickness as demonstrated in this chapter. 

As mentioned previously, mesoscale crystalline morphologies and molecular orientation of HT-PATs in solution-deposited films can be controlled through different solution-processing methods and subsequent thermal treatments [15,17,23,35,36,44,59,89]. Figures 5.2.18 and 5.2.19 represent typical examples for tunable crystalline morphologies and molecular orientations of HT-PHT in solution-deposited films. First, in terms of mesoscale morphologies, HT-PHT (M = 18.8 kDa) films drop-cast from CHCI3 show weU developed nanofibrils interconnected with each other, while the spin-cast... 

The second type of photosensitive SWNT-FET devices adopts SWNT networks as the transistor channel. A polymer layer is then deposited over the contacts and nanotubes by a drop-casting or spin-coating method. As shown in Figure 3.6, the coating of photosensitive polymer doesn t significantly... 

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