My researche field is solar cell and I simulate silicon solar cell with Silvaco TCAD. Typically, open cirtuit voltage and open circuit current decrease with the depth of PN junction increasing. However, I find different rule in my Silvaco TCAD simulation. When the deapth of PN junction is tiny. Sometime open cirtuit voltage and open circuit current climb up and then decline with the depth of PN junction increasing(NA=1*1014, ND=1*1015). Sometime open cirtuit voltage and open circuit current decrease with the depth of PN junction increasing(NA=1.7*1016, ND=5*1019).
in first ,
The open-circuit voltage, VOC, is the maximum voltage available from a solar cell, and this occurs at zero current. ... VOC decreases with temperature. If temperature changes, I0 also changes
By studying the light intensity de- pendence of the open-circuit voltage (VOC), this research shows that in current organic BHJ solar cells the open-circuit voltage is strongly affected by losses. ... More specific, S decreases for increasing intensity.
The short-circuit current from a solar cell depends linearly on light intensity, such that a device operating under 10 suns would have 10 times the short-circuit current as the same device under one sun operation.
The decrease in the band gap of a semiconductor with increase in temperature is an increase in the energy of electrons in the material. Lower energy is thus required for breaking the bond. ... The open circuit voltage decreases with temperature decrease because of the temperature dependence of I0.
Dear Wang Triumph ,
At first please take care of your terminology. The solar cell has a shortcircuit current and opencircuit voltage.
The most important solar cell parameters according to the one junction model are:
The shortcircuit current Iph
The reverse saturation current Is,
The opencircuit voltage Voc = nVt ln Iph/Is,
The main parameter in the Iph is the recombination losses. If the recombination losses increase Iph decreases.
Likewise, the main factor affecting the reverse saturation current is minority carrier lifetime if it decreases Is increases. So, Is increases by increasing the recombination rate.
If both Iph decreases and Is increases then Voc will decrease.
This can explain the your observed decreases of both Iph and Voc by increasing the junction depth of the emitter in the single crystal Si solar cell.
I would like that you refer to the book chapter in the link:Chapter Solar cells and arrays: Principles, analysis and design
which can fully assist you in interpreting all your results.
It gives detailed analytical solution of the solar cells.
Best wishes
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