Films spin coating

The electronic absorption spectra of dilute (typically 5-10 mg/1) solutions of poly(9,9-dialkyl-fluorenes) show a sharp peak with Amax 385-390 nm (3.2 eV) of tt-tt electronic transition. Thin solid films (spin coated from 15 to 20mg/ml solutions) reveal similar absorption with a slightly red-shifted ( 10 nm) and relatively broader peak (due to intermolecular interaction) (Figure 2.9) [246],... 

Colloidal silica films spin-coated onto a glass substrate constitute another method to increase the surface area and therefore number of capture sequences which can be available for hybridization [43]. In this context, 0.3 p,m layers have been deposited from 20 wt % colloidal silica suspensions (particle size 16 to 65 nm). Heating to 350 °C for four hours is required to render the films sfable (fhrough parfial sinfering of fhe film with the underlying substrate). The particles pack randomly with no noticeable short- or long-range order. 

Fig. 5.20. AFM images (acquired in the tapping mode) showing the surface morphology of MDMO-PPV PCBM blend films (1 4 by wt.) with a thickness of approximately 100 nm and the corresponding cross-sections, (a) Film spin-coated from a toluene solution, (b) Film spin-coated from a chlorobenzene solution. The images show the first derivative of the actual surface heights. The cross-sections of the true surface heights for the films were taken horizontally along the dashed lines...

Radiation effects of ion beams on PMMA films spin-coated on silicon wafers have been studied by ion beam pulse radiolysis. Figure 12 shows typical emission spectra of PMMA irradiated by 1 MeV nitrogen ion beams. The spectra changed drastically on irradiation. 

Infrared spectra were recorded on a Perkin-Elmer Model 983G double-beam spectrophotometer in the transmission mode using 3500 A thick PBTMSS films spin-coated and processed on polished NaCl plates. Spectral subtraction and absorbance correction to account for the decreased film thickness were used to isolate the silicon oxide absorption band at about... 

As mentioned in Sect. 2.2.1.3 [33], we proposed that a trace amount of /3-phase, induced by the use of an electron-deficient moiety (TAZ) as an end-capper for PFO, can improve device performance to give a better blue purity. Following the idea of /3-phase formation, we further proposed a novel simple physical method to generate /3-phase at a content of up to 1.32% in a PFO film spin-coated on a substrate (the remaining part is amorphous phase) by immersing it in a mixed solvent/non-solvent (tetrahydrofuran/methanol) for a few seconds [45]. The device based on PFO with 1.32% / -phase (ITO/PEDOT PSS/emitting polymer/CsF/Al) has a dramatically enhanced device efficiency and an improved blue-color purity of 3.85 cd A-1 (external quantum efficiency, 3.33%) and CIE of x+y = 0.283 (less than the limit of... 

Interest in the synthesis and processing of mesoporous silica materials has grown extensively since their discovery in 1992, and the exciting potential that these films hold in low-k dielectrics, sensors, nanowire fabrication, catalysis, membrane separations, and many other applications will continue to fuel academic and industrial interest in these films. While there are many new synthesis routes for processing mesoporous silica thin films, spin coating and dip coating remain the most facile methods available. These methods deliver high quality reproducible films that can be used for any of the variety of applications. 

Thin film dielectrics are usually deposited using chemical vapor deposition (CVD). A variation of CVD utilizing a plasma discharge is called plasma-enhanced CVD (PECVD) and is the standard in IC fabrication for the deposition of dielectric films. Plasma-enhanced CVD involves the formation of a solid film in a substrate surface from volatile precursors (vapor or gas) in a plasma discharge. The precursors are chosen to contain the constituent elements of the final film and chemical reactions in the gas phase are encouraged. They are condensed in a substrate that is heated or cooled. It will be shown later that porosity can be introduced in the PECVD films. Spin coating is another preparation technique and a popular choice... 

Fig. 49 AFM images of PFB F8BT film spin-coated from xylene solution clearly demonstrating phase separation to exist on two scales. Left height images right phase response images, a 10 p,m x 10 p,m and b 500 nm x 500 nm, which was taken in the vicinity of the sample marked by the white square in (a). (Reprinted with permission from [236], 2004, American Chemical Society)...

Fig. 63 Low-voltage scanning electron microscopy of Ti02 films spin-coated at different relative humidities (Rti). Images a-e have identical scale, while f shows a higher magnification of the film spin-coated at 53% Rti. (Reproduced with permission from [305], 2005, Wiley VCH)...

Figure 21.6 Cls XPS spectra of a P(VDF-TrFE) film, spin-coated onto an Al/Si substrate (bottom electrode structure). Thick solid curve just after spin coating. Dashed curve after thermal armeahng at 135 °C for 2 h. The concentration for spin coating is 0.1 wt% P(VDF-TrFE) in 2-butanone. Spectra are corrected for 0.4 eV and normalised with reference to the bulk film, also shown (thin solid curve).

In a typical experiment, polyphthalaldehyde was dissolved in bis-(2-methoxyethyl) ether or cyclohexanone, to which was added the onium salt at 10 wt% to the polymer. Films spin coated on Si wafers were baked at 100°C for 10 minutes and then image-wise exposed. Optical micrographs of the resist images generated upon UV, e-beam, and x-ray radiations are exhibited in Figures 7a, b, and c, respectively. 

If the demands for tightness of the films are less stringent or irrelevant, other methods can be used for the formation of zeolite films. Spin-coating of zeolite suspensions (with nanoscale zeolite crystals) as well as molecular assembly of pre-synthesized zeolite crystals are viable methods for the deposition of rather smooth films. Furthermore, electrophoresis was successfully used to attach zeolite crystals to electrically conducting substrates. 

Time-resolved PL measurements were also performed using time-correlated single-photon counting (TCSPC) and photoluminescence upconversion (PLUC) spectroscopies. Descriptions of the setups can be found in refs. [14, 65], respectively. All measurements were taken in continuous-flow He cryostats (Oxford Instruments OptistatCF) under inert conditions. Finally, PL efficiency measurements were performed on simple polymer thin films spin coated on Spectrosil substrates using an integrating sphere coupled to an Oriel InstaSpec IV spectrograph and excitation with the same Ar+ laser as above. 

The energy barrier for hole injection at the metal-poymer interface is determined by the vacuum work function of the metal contact and the ionization potential Ip of the polymer. For conjugated polymer films spin-coated onto hole injecting metal electrodes, it has been reported that as long as is smaller than a critical value characteristic of the polymer, no interface dipole is formed [104]. In this case, the barrier for hole injection can be estimated simply by aligning the vacuum levels of the metal and the polymer (Mott-Schottky limit) the measured work function of the metal with the polymer deposited on top increases linearly with with a slope of one (see Figure 2.3.11). 

D GIXRD patterns of 1 1 RR-P3HT PCBM films (spin-coated at lOOOrpm) fabricated with different ty (a) 30s and (b) 80s. ID out-of-plane (c) X-ray and (d) azimuthal scan (at ij(lOO)) profiles extracted from (a) and (b). (Reused from li, G. et al., Adv. Funct. Mater., 17, 1636, 2007. With permission.)... 

Fig. 1.13 a Structures of bi-UPy photochromic dithienylethene 45 and mono-UPy-terminated fluorescent dye FI b Depiction of the energy transfer (ET) process of the thin film spin coated from solutions of 97 3 4S-F1 under UVA is irradiation, (green open form of 45 purple closed form of 45 yellow FI) Reproduced from Ref. [112] by permission of John Wiley Sons Ltd... 

Fig. 1.17 CD spectra of PMBET recorded at room temperature from thin films spin-coated onto glass plates after fast (a) and slow (b) cooling from 200°C to 20°C. Adapted from Bou-man et al. [47] with permission from Wiley-VCH.

Made), W., Budkowski, A., Raezkowska, J., Rysz, J. Breath figures in polymer and polymer blend films spin-coated in dry and humid ambience. Langmuir 24(7), 3517-3524 (2008)... 

Huang, X. Pelegri, A. A. Nanoindentation Measurements on Low-k Porous Silica Thin Films Spin Coated on Silicon Substrates. Journal of Engineering Materials and Technology 125, 361-367 (2003). 

Working in collaboration with Reynolds, we have fabricated organic photovoltaic devices in which the active materials were assembled by using the LbL method [53]. In this work, the donor and hole transporting materials were the anionic CPEs PPE-SOs and PPE-EDOT-SO , whereas the acceptor and electron transport material was a cationic fullerene derivative, Cso-NHa (Scheme 14.13). The active layers were constructed atop an ITO substrate that was precoated with a PEDOT-PSS film (spin-coated). The PPE(—)/C6o—NHa bilayers were deposited through the LbL method, and the effect of active layer thickness on device performance was explored. Figure 14.20 shows a schematic... 

The absorption spectra of the left-right unsymmetrically substituted spiro-oxadiazoleamines are all characterized by two peaks. The most intense absorption maximum in dichloromethane solution was determined to be 389 nm for Spiro-AMO-tBu 111, 374 run for Spiro-AMPO-tBu 113,400 nm for Spiro-AMO-CN 112, and 383 nm for Spiro-AMPO-CN 114. All compounds show intense fluorescence in solution as well as in the sohd state (amorphous film spin-coated on glass substrate) and exhibit large Stokes shifts. The values for the emission maximum in solution are 477 nm (Spiro-AMO-tBu), 497 nm (Spiro-AMPO-tBu), 541 nm (Spiro-AMO-CN), and 540 run (Spiro-AMPO-CN). 

Photosensitivity. 1 was dissolved in 20wt% diglyme at 40 C, and to this solution were added MBHP and DIAS. Films spin-coated on silicon wafers were prebaked at 80 °C for 10 min and exposed to a filtered super-high-pressure mercury lamp. Imagewise exposure through a mask was carried out in a contact-printing mode. 

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