Dear Amr,

welcome,

can you display the curves of Rs and Rsh versus the temperature?

Also, it si required to give the construction of the solar cell since the resistance depends on the materials.

Rs is the resistance of the layers of the solar cells in the direction of current flow. Normally he organic material has a resistivity much higher than that of silicon. Therefore the the resistance of the organic layer controls Rs. It is known that the mobility of the charge carriers increases with temperature for organic materials an hence the resistance will be smaller upon increasing the temperature.

It seems me that the shunt resistance is controlled also by the same mechanism as the series Resistance. It can that  there exist small areas of the organic material touches the silicon without forming junction and hence act as a shunt path or leakage area.

wish you success

Hi Amr,

Series ans shunt resistance are due to many  factors, high surface defect density at interface, high ideality factor, non-Ohmic contacts  etc. Actually, by increasing temperature.. we are trying to improve the crystallinity as well as to decrease defect states. The slope of dV/d(lnI) provides the series resistance..in I-V curve.

-- How large are your samples? What absolue values for series resistance and shunt resistance did you obtain?

-- What "receipe" do you follow for determining series resistance and shunt resistance? Could you provide an equation or a reference?

Thanks Dr Wagner for your answer 

The values of the series, Rs, and shunt, Rsh, resistances are determined by plotting the junction resistance RJ as a function of the forward and reverse bias potentials of the junction . At the high forward voltages, the junction resistance reaches a constant value, which is equal to Rs. The same behavior also occurs in reverse bias voltages leading to determination of the value of Rsh. where RJ =  әV⁄(әI ), which can be determined from the current–voltage curves.

OK -- so you determine the limiting values of the slope of your I--V curves (more precisely: of the inverse, i.e. the slope of voltage versus current) for various temperatures. Remember that in the standard pn junction equation (Shockley equation), the thermal voltage occurs. And because of that, the I--V curve changes with temperature even for a hypothetical perfect device without series resistance and with infinite shunt resistance. Would your method determine this correctly?