Solar cells short circuit current

R.J. Matson, K.A. Emery, R.E. Bird, Terrestrial solar spectra, solar simulation and solar cell short-circuit current calibration A review. Solar Cells 11, 105-145 (1984)... 

The optical properties of electrodeposited, polycrystalline CdTe have been found to be similar to those of single-crystal CdTe [257]. In 1982, Fulop et al. [258] reported the development of metal junction solar cells of high efficiency using thin film (4 p,m) n-type CdTe as absorber, electrodeposited from a typical acidic aqueous solution on metallic substrate (Cu, steel, Ni) and annealed in air at 300 °C. The cells were constructed using a Schottky barrier rectifying junction at the front surface (vacuum-deposited Au, Ni) and a (electrodeposited) Cd ohmic contact at the back. Passivation of the top surface (treatment with KOH and hydrazine) was seen to improve the photovoltaic properties of the rectifying junction. The best fabricated cell comprised an efficiency of 8.6% (AMI), open-circuit voltage of 0.723 V, short-circuit current of 18.7 mA cm, and a fill factor of 0.64. 

Fig. 3.17. Structure of the 9.35%-efflcient Basol solar cell, with open-circuit voltage 0.73 V, short-circuit current 20 mA cm, and fiU factor 0.64. (Reproduced from [86])...

Illumination of solar cells causes a reduction of efficiency and fill factor, as a result of light-induced creation of defects (Staebler-Wronski effect. Section 1.1.2.5). This reduction is halted after several hundred hours of illumination. The reduction is correlated with solar cell thickness. A large intrinsic layer thickness leads to a large reduction of efficiency and fill factor compared to a small intrinsic layer thickness. The solar cell properties can be completely recovered by annealing at about 150°C. The open circuit voltage and short circuit current decrease only slightly. 

The PV characteristics of the CIGS2 thin-film solar cell on opaque Mo back contact, as measured at the NREL under AM 1.5 conditions, were as follows short-circuit current density sc of 20.88 mA/cm2, open-circuit voltage 1% of 830.5 mV, fill factor FF of 69.13%, and PV conversion efficiency // of 11.99%. 

He, I. Zhong, C. Huang, X. Wong, W.-Y. Wu, H. Chen, L. Su, S. Cao, Y., Simultaneous enhancement of open-circuit voltage, short-circuit current density, and fill factor in polymer solar cells. Adv. Mater. 2011, 23, 4636-4643. 

The preceding sections described molecular interactions important in organic solar cells. This section discusses the impact of those interactions on the overall device behavior. Simulated electrical behavior for a typical solar cell is illustrated in Fig. 10. Under forward bias voltages 0 < V < Vqo typical photovoltaic device under illumination supplies power (P = / x V) to the external circuit (cf. lower panel of Fig. 10, dashed trace in first quadrant). The formalism used here implies that, under reverse bias, the organic material is reduced at the anode and oxidized at the cathode, while, under forward bias, the organic material is oxidized at the anode and reduced at the cathode. The short circuit current, J c, is approximately equal to... 

Fig. 10 Simulated solar cell electrical behavior in the dark dotted traces) and under illumination (solid traces) comparing the effect of the saturation current parameter 7 on Foe- The black traces represent a device with /g x 10 that of the device represented by the red traces. The sharp inflection points in the semilog plots (upper panel) are the points where the current switches from positive to negative. Also illustrated in the linear representation (lower panel) are the short circuit current density, J c, and the maximum output power, Fmax. given by the product of current and voltage. The blue arrows represent the point at which the dark current and the current under illumination are equal in magnitude. The corresponding potential marked in blue on the voltage axis is Foe for the black trace...

Emery KA, Osterwald CR (1986) Solar-cell efficiency measurements. Sol Cells 17 253 Matson RJ, Emery KA, Bird RE (1984) Terrestrial solar spectra, solar simulation and solarcell short-circuit current calibration - a review. Sol Cells 11 105... 

Figure 13 Dependence on 10-MeV-proton and 1-MeV-electron fluence of the remaining factor of short circuit current (Isc) for Si-BSFR solar cells. Circles and squares represent the results for samples irradiated with 10-MeV protons and 1-MeV electrons, respectively. Broken lines represent the fitting results based on a model mentioned in the text.

Photoelectrochemical cells with polythiophene film as an active electrode and a lead plate as a counter electrode in Pb (C104) acetonitrile electrolyte has an open circuit voltage of 0.8 V, short circuit current of 2 x 10 4 A cm-2, efficiency coefficient of 0.03%, fill factor of 15% [194]. The absorption and photosensitivity spectra of such a cell are shown in Fig. 24. The small bathochromic shift in the longwave region for photosensitivity may be related to the photogeneration of the charge carriers via surface states. The photosensitivity maximum is close to the maximum solar intensity. The parameters exceed the ones obtained with polyacetylene. 

Figure I. Results of an 8-month outdoors test of PEC containing a 0.8-cm2 thin film, painted CdSe photoelectrode (not photoetched), CoS counterelectrode, and 7M KOH, 2M S, 7M S, ImM Se solution. (OCV) open-circuit voltage (SCC) short-circuit current (EFF) solar conversion efficiency ( AMI.5). Between measurements the cell operated on maximum power (68 fi load). No appreciable change in fill-factor occurred during the test.

Under illumination with a light source, a typical solar cell exhibits the current-voltage characteristics shown in Figure 3. The current drawn by the cell when the terminals are connected to each other is the short circuit current (7SC, in mA/cm2). In the presence of an external load with infinite resistance (open circuit condition), the voltage developed is the open-circuit voltage (Voc, in V). 

In a bulk-heterojunction photovoltaic cell with methanofullerene [6,6]-phenyl C61-butyric acid methyl ester (PCBM) as an electron acceptor, alternating copolymer 19 (Fig. 9), derived from 2,7-fluorene and 2,5-dithienylsilole, can show impressive performance as the electron donor.31 In a device configuration of ITO/PEDOT/active layer/Ba/Al, the dark current density—bias curve shows a small leakage current, suggesting a continuous, pinhole-free active layer in the device. Under illumination of an AM 1.5 solar simulator at 100 mW/cm2, a high short-circuit current of 5.4 mA/cm2, an open-circuit voltage of 0.7 V, and a fill factor of 31.5% are achieved. The calculated energy conversion efficiency is 2.01%. 

The flexible solar module based on monocrystalline silicon cells with higher efficiency than thin film solar cells was developed in the VIESH. For example, the folding solar module 36/1-6-P depicted at FigurelO supplies 10W, output voltage 16V, and short circuit current, 0.7A under standard conditions of measurements. His dimensions are 395 x 370 x 4 mm and in the folded condition practically 6 times less by surface (135 x 185 x 12 mm). This folding solar module can be used for applications which small consuming equipment. 

Fig. 8.2. J/V-curve with description of solar cell parameters efficiency /, fill factor FF, open circuit voltage Voc, and short circuit current density Jsc- The photogenerated current density Jph is indicated by the dotted line. More details of these and all other parameters are given in the text...

---