Fill-factor

For Si MIS cells the best fill factors (FF) obtained have been 

The FF also indicates the quality of the photodiode. Counter diode will lead to a negative curvature of the J-V curve in the fourth quadrant and reduce the FF below 25%. Large serial resistance and small parallel resistance can also reduce the FF. In addition, high FF value requires a photovoltaic device with a strict selection 

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Severe corrosion, Rough tubing, Probe wear. Centring, Fill factor, Noise... 

Advantages. Compared to DOR, a small rotor can be used allowing relatively fast spiiming speeds high RF powers can be attained and if the coil is moved with the rotor a good filling factor can be obtained. In the isotropic dimension high-resolution spectra are produced and the second dimension retains the anisotropic information. 

Other frequently used resonators are dielectric cavities and loop-gap resonators (also called split-ring resonators) [12]. A dielectric cavity contains a diamagnetic material that serves as a dielectric to raise the effective filling factor by concentratmg the B field over the volume of the sample. Hollow cylinders machmed from Ilised quartz or sapphire that host the sample along the cylindrical axis are conunonly used. 

Fig. 7. Model calculations for the reflectivity (a) and the optical conductivity (b) for a simple (bulk) Drude metal and an effective medium of small metallic spherical particles in a dielectric host within the MG approach. The (bulk) Drude and the metallic particles are defined by the same parameters set the plasma frequency = 2 eV, the scattering rate hr = 0.2 eV. A filling factor/ = 0.5 and a dielectric host-medium represented by a Lorentz harmonic oscillator with mode strength fttOy, 1 = 10 eV, damping ftF] = I eV and resonance frequency h(H = 15 eV were considered for the calculations.

The geometrical factor, like the filling factor, shifts the position of the resonance peak. When = 0 we have the case of an infinite cylinder (see Table 1). An infinite cylinder connects one side of the crystal to the other. Therefore, the electrons travel freely through the crystal. Actually, this is not the situation of metallic particles dispersed in an insulator any more. The situation corresponds... 

Fig. 8. Calculations performed considering metallic spherical particles (i.e., N = 1/3) with intrinsic Crude parameters fttOp = I eV, fiV = 0.01 eV, dispersed in an insulating matrix with parameters fttOp i = 2 eV, ftP] = I eV and fttO] = 5 eV, and filling factor /between 0.2 and 1.

The first act consists of removing a small part of the insulator (e,) and replacing it by a small amount df of metal (E,n)- Thereafter with Eq.(6), we calculate Ef,fj( ). For the first step, there is no difference with MG. If we now add another amount df2 of metallic particles (e, ) in the brand new system (e l)), we can again calculate the new effective dielectric function with Eq.(6). Instead of using / for the dielectric function of the host, we now use ej (l) obtained by the previous step. Since we removed some insulating material and replaced it with metal, we have to replace the filling factor/by dfil -//-]).//-i is the amount of metal already in the material and /// the metal we add at step i. The... 

The main phenomenological difference in BM compared to MG is a broadening of the resonance peak at which, however, does not shift. The model calculations in Fig. 11 have been performed for spheres (N = 1/3) with filling factors of 0.5 and 0.9. The parameters, chosen to be equal for both models, are given in the figure caption. It immediately appears that we will not find any drastic difference in the interpretation of the data for the MG or the BM model. 

Table 2. These parameters refer to the Maxwell-Garnett (Eq.(6)) and Bruggeman calculations with a filling factor f 0.6. N denotes the geometrical factor. All other values are in eV.

The filling factor is in good agreement with estimation from electron microscopy [6]. A filling factor of about 0.6 was obtained in all cases. The filling factor sensitively determines the position of the resonance at 0), which indeed shifts in frequency for different specimens. Moreover it is important to observe that / is already quite large and close to the boundary value for a percolation limit (which is -0.7 for spheres and -0.9 for cylinders). The realisation of such a limit would lead to a low frequency metallic Drude-like component in ai(to) for the composite. At present, this possibility seems to be... 

There is experimental consensus on the most important parameters of singlelayer polymer photovoltaic devices, the short circuit current / , the open circuit voltage V c, and the filling factor FF. From these parameters the efficiencies of PPV based devices were typically calculated to be around 0.1% under monochromatic low light intensities. Efforts to extend the classical semiconductor picture of... 

The compounds were mixed in three steps The first two steps were done in an internal mixer with a mixing chamber volume of 390 mL. The mixing procedures employed in the first two steps are indicated in Table 29.2. The starting temperamre was 50°C and the cooling water was kept at a constant temperature of 50°C. The rotor speed was 100 rpm and the fill factor 66%. After every mixing step the compound was sheeted out on a 100-mL two-roll mill. The third mixing step was done on the same two-roll mill. The accelerators and sulfur were added during this step. 

The dump temperature of the compound was varied by changing the mixer s rotor speed and fill factor while keeping the other mixing conditions and the mixing time constant. Under the assumption that the final dump temperature is the main parameter influencing the degree of the sUanization reaction, the effect of the presence of ZnO on the dynamic and mechanical properties of the compound was investigated. ZnO was either added on the two-roll mill or in the mixer. 

FIGURE 29.11 Effect of silanization in an open mixer on the Payne effect for different mixer types and fill factors (silanization time 150 s, temperature 145°C, T4 tangential 3.6 L, 15 intermeshing 5 L, 145 intermeshing 45 L, T7 tangential 7 L). 

Figures 29.11 and 29.12 demonstrate the results of the silanization efficiency for different mixers and different fill factors under standard conditions (closed mixer) compared to working with an open mixer. The silanization efficiency is measured by viscosity and Payne effect.

Standard fill factor Optimized fill factor ... 

FIGURE 29.13 Influence of air injection on the silanization efficiency (mixer volume 45 L, fill factor 0.4, silanization temperature 145°C, time 150 s). 

Reduction of the fill factor in order to improve the intake behavior when working in an open mixer has an additional positive effect on the silanization efficiency. A combination of both measures, silanization in an open mixer and reduction of the fill factor, leads to further improvement. 

To summarize, the kinetics of the silanization reaction are strongly influenced by the efficiency of the devolatilization process. The degree of devolatilization mainly depends on processing conditions (e.g., rotor speed and fill factor), mixer design (e.g., number of rotor flights, size of the mixer), and material characteristics. The diffusion coefficient of the volatile component in the polymeric matrix is of minor influence. 

Typical values for the fill factor are 0.6-0.8 depending on the compound s recipe and the type of rotors being applied. 

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