Dear Velayutham,

welcome,

You measure the i-v characteristics of a solar cell in dark as you measure the I-V characteristics of a diode. You a apply a stepped voltage on it and measure the cell current my DC milliammeter either for forward bias and reverse bias, So that you obtain a curve. Naturally, you have to keep your cell in darkness.

You need such measurements because you can predict from it how far you solar cell is working properly before you measure the illuminated I-V characteristics.

Theoretically speaking, the illuminated I-V curve of well functioning solar cell is a superposition of its dark curve and the photcurrent Iph.

This is one thing. The other thing is that we can determine some of the cell performance parameters from the dark I-V curve. namely:

- The shunt resistance, ideally infinite

- the series resistance, ideally zero

- The ideality factor ideally one, in some cells two

- the reverse saturation current, ideally as small as possible

In addition if one plots the dark and illuminated curves together and the illuminated crosses the dark, this means that the cell does not satisfy the superposition principle and has problems with photocurrent collection process and or nonlinear metal semiconductor contacts.

I treated these problems in my papers and my posts in the researchgate

Best wishes

I think that the following paper might be helpful to you:

Measuring methods of cell performance of dye-sensitized solar cells

Review of Scientific Instruments 75, 2828 (2004); https://doi.org/10.1063/1.1784556

The paper dealt with J-V characteristics under AM-1.5 irradiation but the same procedure for the J-V measurements would be very important for DARK J-V measurements.

Namely (from the abstract of the paper mentioned above), "To improve accuracy, measurement should be carried out with a sampling delay time exceeding several seconds. "

Dear Velayutham,

welcome,

You measure the i-v characteristics of a solar cell in dark as you measure the I-V characteristics of a diode. You a apply a stepped voltage on it and measure the cell current my DC milliammeter either for forward bias and reverse bias, So that you obtain a curve. Naturally, you have to keep your cell in darkness.

You need such measurements because you can predict from it how far you solar cell is working properly before you measure the illuminated I-V characteristics.

Theoretically speaking, the illuminated I-V curve of well functioning solar cell is a superposition of its dark curve and the photcurrent Iph.

This is one thing. The other thing is that we can determine some of the cell performance parameters from the dark I-V curve. namely:

- The shunt resistance, ideally infinite

- the series resistance, ideally zero

- The ideality factor ideally one, in some cells two

- the reverse saturation current, ideally as small as possible

In addition if one plots the dark and illuminated curves together and the illuminated crosses the dark, this means that the cell does not satisfy the superposition principle and has problems with photocurrent collection process and or nonlinear metal semiconductor contacts.

I treated these problems in my papers and my posts in the researchgate

Best wishes

The curves IV in darkness are so important. From these curves you can study the transport mechanisms as diffusion or recombination. You can evaluate that in direct polarization in a semilog graph. Wiley: Physics of Semiconductor Devices, 3rd Edition - Simon M. Sze It is also important to extract the reverse saturation current and the ideality factor since they strongly impact the open-circuit voltage of your solar cell. I hope it helps you. regards

Dear Velayutham,

The emerging PV, DSSC, PSC, ..., have the capacity effect and hysteresis effect. Therefore, I-V of the device show forward/backward can't overlap.

If you want to improve accuracy under I-V measurement, some test method can refer from

https://www.researchgate.net/project/Performance-rating-measurement-of-emerging-PV-for-Outdoor-Solar-AM15G-and-Indoor-lighting/update/5a1ccc354cde267c3e6f269a

or

https://www.researchgate.net/project/Performance-rating-measurement-of-emerging-PV-for-Outdoor-Solar-AM15G-and-Indoor-lighting

Thank you.

Best wishes

Mickey