3D pillar solar cell short circuit difference between FDTD and DEVICE



G.mat (5.9 MB)
After running, there will always be an error as shown in the figure below. How can I solve this problem?
image doping (1).lsf (2.9 KB)



I was not able to reproduce the error on the file you attached. Please make sure you attach the file that gives the error and includes any data you use such as generation. Also, please elaborate on what you are trying to simulate.


After re-running, the same errors will still occur. The G file in the uploaded model is not imported and needs to be imported at run time. The script file is a confusing file for the arrays. It is hoped that the efficiency of the solar cell can be simulated by this physical model.


It think there are some issues in your simulation setup that might cause this issue:

  1. There are two generation and two doping objects with the same dimensions at the same location. Make sure there is either just one for each or they are located at a different location.
  2. As show below, the generation rate data (purple box) does not match the simulation region in terms of dimensions and location. This is necessary for a proper simulation.



2018.12.17 (1).ldev (7.1 MB)

G12.21.mat (5.9 MB)

Thanks for your guidance, and made the appropriate changes based on your guidance, but the same error will still occur after the run. I have read the forum about Gaussian’s explanation, but I would like to ask you about the Gaussian part. I don’t understand where Gaussian should be set, and what is the basis for its ref concentration setting.


I ran your file as is (after importing the generation data) and it ran with no problem. Make sure you are running the latest version of DEVICE.
Regarding the diffusion doping profile, see the topic below:


Under your guidance, the simulation is indeed converging. But the result of the operation is very strange. I hope to output the current and voltage characteristics through a script. After running, I found that the output voltage is larger than the voltage I set and the short-circuit current is negative. Other output parameters are 0. I would like to ask why. The value of the voltage becomes larger and the short-circuit current is negative. The following file is a script that outputs parameters such as open circuit voltage short-circuit current.

Jsc_Voc.lsf (1.5 KB)


I see two main issues in your simulation:

  1. A solar cell is supposed to be forward biased for power generation but yours seems to be currently reverse biased.
  2. Your optical generation is correctly defined for a unit cell of the structure as shown below but your electrical simulation is not. You might wanna make sure that the CHARGE simulation region has the same span as your generation data.



Do you mean that the direction of the voltage setting is reversed? Should the value in ‘base’ be fixed to 0 and the value in ‘emitter’ set to 0-1V?


Yes, in a pn junction, for a forward bias, the p side should have a positive voltage applied or vice versa.


Thank you for your guidance. After running under your guidance, I found that the short-circuit current density is only about three, which is normally around 30. May I know what is the reason? Also would like to ask what is the connection between the short-circuit current in the FDTD section and the short-circuit current in the DEVICE section?
solar_silicon_pillar_plot_JV.lsf (637 Bytes)
G12.21.mat (5.9 MB)


A lot of things can affect the short circuit current. How much is the value returned by FDTD?

The value returned by FDTD is ideal (in case all the photogenerated charges were to be collected, which is never the case) where as DEVICE returns the more realistic values considering the electrical losses reducing charge collection efficiency

Any reference or measurement for this value?


The short-circuit current calculated in the FDTD section is more than one hundred, which is much different from the DEVICE. In the description, see an example (2D silicon square grating), which analyzes and compares the short-circuit current of these two modules should not have such a large error.

在DEVICE 部分模拟结果短路电流过小

This issue still exists in the latest version of your simulation and might be contributor to low value you are getting for Jsc


This is the case of the imitation “3D pillar silicon solar cell”, the DEVICE part of the case is one quarter of the FDTD simulation area.Through the case, it is found that the short circuit current of the two modules of the traditional block solar cell is similar. However, in the case of “3D pillar silicon solar cell”, the short-circuit currents of the two modules are quite different. The FDTD part is more than 300, but the DEVICE part is only a dozen. The manual mentions the result of the body/surface compounding, and then considers The short-circuit current can be only about 30 in the absence of recombination. May I know what is the reason?
If the three different materials in the simulation are replaced by the same material (such as si, cds), the short-circuit current will reach about twenty. But once the three materials are replaced, the short-circuit current is only a few. What is the reason?

After doing some experiments, I found that it may be the effect of Eg value, but other software will also need to set Eg but the short-circuit current can still reach dozens. What is the reason? Do different settings be required for semiconductors of different materials to form heterojunctions?


If you look into the code for solar generation object used in the example, you can see that the object reports the Jsc in the units of A/m^2 so you need to convert the value to mA/cm^2 (divide by 10) which then makes sense when comparing to DEVICE simulation