Photocurrent open-circuit voltage

MIM or SIM [82-84] diodes to the PPV/A1 interface provides a good qualitative understanding of the device operation in terms of Schottky diodes for high impurity densities (typically 2> 1017 cm-3) and rigid band diodes for low impurity densities (typically<1017 cm-3). Figure 15-14a and b schematically show the two models for the different impurity concentrations. However, these models do not allow a quantitative description of the open circuit voltage or the spectral resolved photocurrent spectrum. The transport properties of single-layer polymer diodes with asymmetric metal electrodes are well described by the double-carrier current flow equation (Eq. (15.4)) where the holes show a field dependent mobility and the electrons of the holes show a temperature-dependent trap distribution. 

The fill factor is obtained by dividing the product of current and voltage measured at the power point by the product of short-circuit current and the open-circuit voltage. The power point is the maximum product of the cell voltage and the photocurrent obtained on the I V plot (see Section 9.16.4.5). The open-circuit voltage is the potential of the illuminated electrode, where the short-circuit current (7SC) is zero. 

The photocurrent density of nanotube array samples fabricated in an electrolyte of 1.2 g of NH4F in a solution of 5 ml deionized water + 95 ml formamide at 35 V is shown in Fig. 5.46(a). The resulting nanotube array samples were 30 pm in length, with an outer diameter of 205 nm. The samples were annealed at 525°C and 580°C for 1 hour in oxygen prior to measurement. The 580°C annealed sample had an open circuit voltage Voc of -0.925 V (vs. Ag/AgCl) the 525°C annealed sample had an open circuit voltage... 

The overall efficiency, rjsi0bai, of the photovoltaic cell depends on the integral photocurrent density, zph, which represents the overlap between the solar light envelope and the monochromatic current yield, the open-circuit voltage, Voc, the fill factor of the cell iff), and the light intensity, Is, as shown in the following ... 

At high light intensity, the photocurrent discharges the Ca and Cd rapidly, and the potential difference between the Al electrode and the ITO electrode becomes equal to the open circuit voltage for th e a-Si H photodiode. In this... 

Fig. 10.3 illustrates the current-voltage characteristics of a p-i-n sensor in the dark and in light. The photocurrent rapidly saturates in reverse bias when there is full collection of the incident absorbed photon flux. The photovoltaic properties in slight forward bias are characterized by the short circuit current J, the open circuit voltage, Vog, and the fill factor, F. The maximum power delivered by the device is the product of the three terms... 

Figure 22. Photocurrent-voltage characteristic of a nanocrystalline photoelectrochemical cell sensitized with cw-[Ru"(dcbpy)2(NCS)2] /(sc) is the maximum (short-circuit) current density, and K(oc) the maximum (open-circuit) voltage delivered by the cell. The conversion efficiency is calculated by use of Eq. (61).

At their present state of development, ETA cells typically exhibit open-circuit voltages of 0.6-0.7 V and photocurrents of 5-15 mA cm . While the fill factors in the earlier ETA cells were often poor, typically -20%, more recent cells have improved fill factors, typically -60%. Overall, the solar conversion efficiencies are modest, as shown in Fig. 1.2 to date ri p values of approximately 5% have been obtained (Nanu et al., 2005). Insertion of an ultrathin mnnel barrier layer of an insulator such as AI2O3 or MgO can improve the open-circuit voltage (Wienke et al., 2003). Incorporation of quantum... 

Cell characteristics lUumination 500 W xenon lamp. The ITO/P3MT (poly-3-methyl-thiophene) electrode has open-circuit voltage = 0.44 V, short-circuit photocurrent 0.09 luA. cmT, charge efficiency of the storage cell = 40%. 

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