Photovoltaic characteristics

When the cell is short circuited (V= 0), the short-circuit photocurrent Ec flows. With monochromatic illumination, one can obtain from it e.g. the spectral dependence of the charge-carrier generation. The voltage at which the current just ceases to flow is called the open-circuit voltage Voc- It is mainly determined by the energy 

The external quantiun yield or I PC E (incident photon to current efficiency) is defined as the quotient of the number of incident photons and the number of charge carriers output to the external circuit. It is smaller than the internal quantum yield for conversion of the absorbed photons into charge carriers within the cell, because it takes into account losses due to reflection, recombination, and scattering. In contrast to the internal quantum yield, which can attain values of nearly 100% (see above), the value of the external quantum yield can be measured directly from the short-circuit current density jsc. with jsc = Isc/A where A is the active area of the cell, and the incident light intensity is lo- At a given wavelength k, we have 

For low intensities, the short-circuit current jsc is proportional to the intensity Iq-The quantity 

The efficiency rjp is the maximum electric power Pmax per light power Pi, 

For a powerful, effective photocell, one thus requires a large filling factor, a high short-circuit current, and a high open-circuit voltage. It is not sufficient to optimise only one of these quantities if one wishes to produce an efficient photovoltaic cell or solar cell. 

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The nanocarbon-Ti02 Schottky junction plays a crucial role in the photovoltaic characteristics of a semiconductor electrode [89]. According to the thermionic emis-... 

TABLE 15.1 Photovoltaic Characteristics of Dye-sensitized Solar Cell in Various Ionic Liquids at 25°C (AM 1.5, 100 mW cm )... 

Park. B. Han M. (2009). Photovoltaic characteristics of polymer solar cells fabricated by pre-metered coating process. Optics Express, vol. 17, no. 16,13830-13840. 

Feng W, Feng Y, Wu Z (2005) Ultrasonic-assisted synthesis of poly(3-hexylthio-phene)/Ti02 nanocomposite and its photovoltaic characteristics. Jpn J Appl Phys... 

The photovoltaic characteristic is consequently given by (see, e.g., Fahrenbruch and Bube 1983) ... 

The second important mechanism of photogeneration is photostimulation of long-lived stable cation-radicals of the donor PI fragments, representing the hole (major carriers) captured by deep centers (PSC). Accumrrlation of the cation-radieals in the dark and photo processes leads to the dependenee of photovoltaic characteristics on the number of charge discharge cycles of the sample. 

L. Wang, Y. Liu, X. Jiang, D. Qin, Y. Cao, Enhancement of Photovoltaic Characteristics Using a Suitable Solvent in Hybrid Polymer/Multiarmed CdS Nanorods Solar Cells. Journal of Physical Chemistry C 2007, 111, 9538-9542. 

It becomes apparent from Equation 19.12a and Equation 19.12b that accurately measuring the internal fields and built-in potential of diodes would not only assist in the understanding of the physics of the device but also permit the gauging of the energy level lineup of the diodes electrodes. EA spectroscopy is a powerful tool as it enables the investigator to do this, not on model structures, but on real finished devices so that results are directly comparable to the current and luminance or photovoltaic characteristics of the device under study. 

PTPTB is among the first low band gap polymers exhibiting promising photovoltaic characteristics in bulk heterojunction solar cells [73]. It consists of an alternating electron rich N-dodecyl-2,5-bis(2 -thienyl)pyrrole and an electron-deficient 2,1,3-benzothiadiazole unit as shown in... 

M. Y. Song, K. J. Kim and D. Y. Kim, Enhancement of photovoltaic characteristics using a PEDOT interlayer in Ti02/MEHPPV heterojunction devices, Sol. Energy Mater. Sol. Cells 85, 31-39 (2005). 

Figure 18.2 presents a typical current-voltage curve and photovoltaic characteristics that define the performance of solar cell devices. The PCE of the cell depends mainly on the short-circuit current, /sc, the open-circuit voltage, Voc, and the fill factor, FF, as shown in Figure 18.2. 

Thompson, W. G., and Anderson, R. L., Electrical and photovoltaic characteristics of indium-tin oxide/silicon heterojunctions. Solid State Electron., 21, 603-608 (1978). 

Wang L, Liu Y, Jiang X, Qin D, Cao Y (2007) Enhancement of photovoltaic characteristics using a suitable solvent in hybrid polymer/multiarmed Cds nanorods solar cells. J Phys Chem C 111 9538-9542... 

Table 6.1. Physical, optical and photovoltaic characteristics ofPTAl-12, PPVl-8, PTPA 1-3, PFI-6 and PAD 1-6...

Table 6.2. Physical, optical and photovoltaic characteristics ofPMCl-25...

Consequently, electroconductivity (including the many papers of Hanack ) and photovoltaic characteristics are not mentioned. The development of new phthalocyanine compounds with expanded pi-electron systems, such as two-dimensionally polymerized phthalocyanine compounds and dendritic structures, are also outside the scope of this subject matter. 

In addition, some quinacridones have found unusual applications. For example, both quinacridone and its 2,9-dimethyl derivative have been found to exhibit desirable photovoltaic characteristics , and show relatively high power conversion efficiencies in solar cell fabrication. Some quinacridones have also been found to be reasonably good photoconductors, and 2,9-dichloroquinacridone has been shown to be a photoreceptor in electrophotography. A variety of other atypical applications have also been claimed in the patent literature. 

Phthalocyanine compounds exhibit many kinds of electronic, optical, magnetic, and optoelectronic characteristics. To hyperbolize, phthalocyanine compounds can do anything. But, viewed in practical terms, every characteristic of phthalocyanine compounds meets the competitive materials in the market. We have referred principally to application fields where phthalocyanine compounds have superiority over competition. So, for example, electroconductivity, including many works of Hanack [29] and photovoltaic characteristics are not mentioned. The development of new phthalocyanine compounds with expanded 7t-electron systems, such as two-dimensionally polymerized phthalocyanine compounds [30] and dendritic structures [31], have also not been considered. 

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