fundamental question of solar generation fuction

Hi. I'm studyin the FDTD for solar cell.

But there is too many things that I don't know.. So please let me know what is the meaning of the things inside of the red box that i checked.

or, can you let me know related video or files?

and should solar generatio, field and index larger than the structure that I'll simulate?


Best Answer

  • gsungsun Posts: 1,405Ansys Employee
    Accepted Answer

    As a FDTD beginner, it might be helpful to watch edu videos:

    and some KB introduction:

    On your tube there are also some webinar recordings and short videos that you can search and watch:

    Setting up a Simulation in Ansys Lumerical FDTD - YouTube

    list of youtube videos are here

    I understand that learning a new tool is not easy as there are many settings, physics and other related things. But keeping trying, practicing and support you will quickly get started and then you can modify to meet your need.

    You may search in for a specific object, or special "words and phrases", such as "DOWN SAMPLE X"

    Below are my brief replies to your questions:

    1: DOWN SAMPLE is used to reduce the number of data in the frequency-domain monitor. FDTD is a discrete meshing, and the monitor by default will record the fields at every mesh point. To reduce the memory requirement, one can record every other points (down sample of 2), or every 3 points ( down sample of 3). If you have time, please try a few different number, extract the data and check the data matrix size, or the simulated file size.

    2: For frequency domain monitor, by default it uses the parameters set in "global monitor settings" which applies to all the frequency-domain monitors. If you do not want to use them, please tick "override global monitor settings", and you will be able to modify them in the pop up windows.

    all tab settings can be found in this page:

    As for the output quantities, you can choose E, H and others if you want.

    A role of thumb is to use the default settings, only change the default settings when you know why and necessary.

    3: analysis groups are developed for easy use for specific purpose. General description for the analysis groups is here: Analysis Groups - Simulation object

    Analyzing Simulation Results - Analysis Groups - Introduction to Analysis Groups (video)

    Each of the structure groups and analysis groups are self-explanatory by reading the script headers and comments in the script

    For the "solar generation", it first extracts the data, do interpolations to have better accuracy, covert to photon generated charge density. For solar device, the optical period ( plane wave + structure repeat) is different from electric period (charges and contacts repeat), therefore, depending on the electric period, the generated charges need to be created from single period of optics. For example, If there are 18 optical periods (or grating teeth) between contacts, the "periods" should be 18. This requires a prior knowledge of electric simulation. This number actually can be larger but cannot be smaller than the electric period. When it is larger, the CHARGE region can truncate it.

    2D simulations in CHARGE are more popular, since the charges (current) are additive. So one can get the averaged optical generation in 2D, by adding the optical generation in the 3rd dimension.

    This solar example involves both optical and electrical. It might be better to focus the optical simulation first.

    Again learning a software takes time. Please be patient and step by step.


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