External contacting efficiency

The average error for the 105 data points is -7.1% with a standard deviation of the error of 26.1%. The data (65 points ) for external contacting efficiency in the trickle-flow regime (11. 18, 20, 21) can be correlated by ... 

Figure 3 shows the results obtained when the above correlations developed using the more active 2.5% Pd catalyst are applied to data obtained on the less active 0.5% Pd catalyst. It can be seen that the agreement between the model predictions and experimental values is of lesser quality than the previous case. The deviations are especially noticeable with increasing L/us or decreasing external contacting efficiency since the predicted lines cross each other at an intermediate value which is opposite to the data. On a positive note, the predictions are more accurate than those that would be obtained using the literature correlations as shown earlier in Figure 1. Further work is needed to determine the underlying reason for this behavior, however.

A study was performed to ascertain the effect of matrix truncation on calculated values of the catalyst effectiveness for both the Dirichlet and Robin conditions. The results are summarized in Table II for a Thiele modulus of 1.0, an external contacting efficiency of 0.5 and for matrices of size N x N. The answers seem to be accurate on the first two decimal places and the results for Bljj = 10 and Bl = computed from two different expressions agree well. 

The hole current in this LED is space charge limited and the electron current is contact limited. There are many more holes than electrons in the device and all of the injected electrons recombine in the device. The measured external quantum efficiency of the device is about 0.5% al a current density of 0.1 A/cm. The recombination current calculated from the device model is in reasonable agreement with the observed quantum efficiency. The quantum efficiency of this device is limited by the asymmetric charge injection. Most of the injected holes traverse the structure without recombining because there are few electrons available to form excilons. 

While the external quantum efficiency of PS reported for solid-state contacts is usually low, wet contacts are found to give high EL efficiencies at low applied bias under anodic [Vi2, Itl, Ge2, Ha7] as well as cathodic conditions [Bsl]. An example of bright EL from a micro PS sample in acetic acid under anodic bias is shown... 

Tracer methods proposed by Schwartz et al. (19) and Colombo et al. (21) were used to determine total and external catalyst contacting efficiency. These techniques have been described elsewhere (22). Total contacting efficiency, r)c defined as the fraction of total (external and internal) catalyst area contacted by liquid can be obtained by ... 

The variations of the bed scale apparent reaction rate may be interpreted in terms of a contacting efficiency u c and an external efficiency rig (representing the external mass transfer limitaitons). nc is given by... 

Figure 14.3 Current-voltage characteristics likely due to one of the contacts blocking charge (a) and external quantum efficiency spectrum of extraction under forward bias. (Reprinted with a P3HT F8TBT blend device (b). Note that the permission from Ref [11]. Copyright 2007, "kink" in the current-voltage curve about Voc is American Institute of Physics.)...

Fig. 1 Picture of the EL emission of an Al/n Si/l-nm-thick porous siIicon/200 nm-thick ITO device. Orange EL (external quantum efficiency of about 1 %) was emitted through the right ITO electrode, which was biased at — 10 V with respect to the back A1 contact The left ITO electrode was left unbiased. Each electrode was a quarter of a disk of radius 2.5 mm (Gelloz and Koshida 2000)...

The dispersion model with particle diffusion always assumes complete external contacting of particles by liquid which may not be the case in trickle flow. This means that the effective diffusional time constant is increased in trickle flow resulting in a reduced apparent effective diffusivity which is based on the total external surface area. Using this diffusivity in the expression for the Thiele modulus, and equating it to the modulus defined for trickle-bed operation by Dudukovic (130) results in the following estimate of the external catalyst contacting efficiency, UcE ... 

Studies of conjugated polymer-porous metal oxide (i.e., TiOa) structures have focused on optimization of the layer structure of the device and choice of polymer materials. By optimization of the device thickness and electrode choice, groups achieved photocurrent external quantum efficiency (EQE) values of 10,23, and 40 % [36-38]. The reduction of the polymer and TiOa layer thicknesses to the region of 50-100 nm is a key step for this optimization. In polymer-porous metal oxide structures, the porous metal oxide acceptor layer is normally deposited on top of a TCO substrate (i.e., ITO), the polymer is then fabricated on the metal oxide, and an evaporated metal is deposited on top of the active layers as a hole collecting contact. This polarity is the opposite of most commonly reported organic solar cell structures, so the hybrid cell is also called inverted organic solar cell. ... 

CBD from SbCls, NaiSiOs and annealed at 300 °C in a nitrogen atmosphere and cooled in air to allow a passivation layer of S2O3 to form CuSCN, deposited from a solution in 1 1 di-n-propyl sulfide and PrS infiltrated into the pores at 65 °C a 80 nm gold contact was deposited by evaporation. KCN treatment prior to CuSCN deposition was found to increase the short-circuit current as a result of doping with excess SCN . The device was aged for a few days. The IPCE matched the optical spectra of SbiSs and the external quantum efficiency was as high as 80% between 450 nm and 520 nm. The reported efficiency was 3.37% at 1 sun (/sc = 14.1 mA cm Voc = 490 mV, FF = 0.488). 

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