Current—voltage features

An important experimentally available feature is the current-voltage characteristic, from which the terminal voltage ([/v ) supplied by the electrochemical cell at the corresponding discharge current may be determined. The product of current / and the accompanying terminal voltage is the electric power P delivered by the battery system at a given time. 

In Fig. 17 we have presented the current-voltage and the power characteristics of 12-cells battery from the cells type ZV300. It must be reminded that, when the zinc anode in the primary zinc-air cells is discharged, the cell is out of operation. By this, the air electrodes, which in principle can operate for a long time, are lost. In order to avoid this inconvenience, mechanically rechargeable zinc-air cells were developed [14]. The essential feature of the mechanically rechargeable zinc-air cell is that the air electrodes are used many times. 

An STM probe has been used to isolate individual MS (M = Cd, Pb) particles and to measure electronic phenomena (55,56,81). The MS films were prepared either by exposure of metal ion/fatty acid films to H2S (55,56) or by transfer of a compressed DDAB-complexed CdS monolayer (81). All the films were transferred onto highly oriented pyrolytic graphite (HOPG) for the STM measurements. A junction was created at an individual CdS particle with the STM tip as one electrode and the graphite as the other, and the current/voltage characteristics of the panicles were measured. For the particle prepared in the fatty acid films the I/V curves exhibit step-like features characteristic of monoelectron phenomena. In the case of the DDAB-coated CdS particles the I/V measurements demonstrated n-type semiconductor behavior. The absence of steps in this system is probably a reflection of the larger size of the particles in the DDAB films (8 nm by AFM) compared to the 2-nm particle size typically found for MS particles formed in fatty acid films. 

In Fig. 16 we show a current-voltage curve for >-type GaP in the presence of a dye in the dark and at illumination with light being only absorbed by the dye. We see again a saturation current, now however, in cathodic direction. The photocurrent spectrum is represented in Fig. 17. It corresponds fully with the absorption spectrum of the adsorbed dye. One sees a saturation current at a polarisation of more than 0.35 eV negative of the flat band potential. Some special features at GaP-electrodes seem to be caused by the existence of surface states with energies in the range of the band gap. It has been assumed that these surface states can... 

The LSV current voltage curve, often called an LSV wave, for a reversible charge transfer reaction is shown in Fig. 2. The features of interest which are labelled are the peak current (/p), the peak potential (Fp), the reversible potential (Exev), and the half-peak potential (iJp/2). 

We have, at this point, examined some rather complex features of the current-voltage (i-V) curve. As you are now aware, it is affected by the nature and concentration of the electroactive species, by the electrode material, and by the mode of mass transport. The general equation that describes the current density j as the function of applied voltage E is... 

To generate large pressure, a stack structure of many piezoelectric plates and metal electrodes is used. Pressures greater than 350 kgf/cm2 are obtained. The maximum stroke is, however, small. The stroke to length of the actuator is smaller than 10 3. A high applied voltage of over 100 V and a small current are features of this actuator. 

Table 3.54 gives a summary of the features and applications of the current, voltage, and wattage instruments. Some of these electric meters have been... 

Brabec and coworkers have made extensive measurements of the dark and illuminated currents of MDMO-PPV/PCBM BHSCs [124,141], The experimental results for the BH-SCs from their paper [124] are shown in Fig. 5.22. There are points of inflexion in the dark current of the organic solar cell confirming that the dark current is the space charge limited currents. These features, particularly the points of inflexion, are absent in the illuminated characteristics. At larger voltages the forward dark current intersects the illuminated current and the illuminated current becomes larger than the dark current. 

Fig. 9.27. Current-voltage characteristics of a double barrier structure with well thickness of 40 A, showing the resonant tunneling features. The predicted voltages of the peaks are indicated (Miyazaki ei at. 1987).

Measurements of current-voltage (I/U) characteristics have been made with an account of the concept of tunable electronic material with pores in oxide of semiconductors (TEMPOS) [3-6]. TEMPOS structures, depending on the preparation details, may resemble the features of resistors, capacitors, diodes, transistors, photocells or sensors. It is worth noting that similar I/U characteristics under the influence of humidity were observed earlier [4] on the TEMPOS samples consisting of a SiOi layers with ion tracks covered with continuous fullerite layers on Si substrates. This structure has got the name of MOSBIT (moistutre sensor with buckminsterflillerene in the tracks). 

There are new features of performance if both transport limitations are present at the same time. Understanding them takes more effort and a more general consideration, which, however, also leads to clear-cut conclusions on the current-voltage performance and the profile of p(x) and... 

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