Solar Cells Simulation using Lumerical Tools (Part 2 - Lumerical FDTD)
Introduction to Numerical FDTD
In this session, we will explore the numerical FDTD (Finite-Difference Time-Domain) method using Lumerical tools. We will start by opening a solar cell example.
Waveguide Definition
In numerical FDTD, you can define your structure using various items such as triangular, rectangular, and circular waveguides. For example, you can add a circular waveguide and modify its geometry, including the X and Y dimensions, radius, material, and other parameters.
Solar Cell Example
Let's begin with a solar cell example:
- Enable the base and edit its properties. The base has an X-span of 3 micrometers and a Y-span of 0.5 micrometers. The material used is aluminum.
- For the aluminum material, we explore its properties using the material explorer, focusing on the wavelength range of 0.3 to 1.1 micrometers.
- Enable the silicon layer. The X-span is the same as the base, but the Y-span is 3 micrometers. The material is silicon.
Simulation Setup
Next, we configure the solver and source:
- Select the FDTD solver and set it for a 2D simulation.
- For the background, use a default material with an index of 1.
- Set the simulation dimensions to 0.5 micrometers in X and 5 micrometers in Y.
- Use a Perfectly Matched Layer (PML) for the Y boundaries and periodic conditions for the X boundaries.
- Configure the mesh settings to auto non-uniform and conformal variant zero.
Source and Monitor Configuration
Configure the source and monitor:
- Set the source to simulate solar light with a frequency range of 0.3 to 1.1 micrometers.
- Use a transmission monitor to record data across the wavelength range.
Running the Simulation
After setting up the simulation, run it and observe the results:
- Monitor the auto shutoff level to determine when the simulation is complete.
- Analyze the results using the solar generation analysis tool to calculate parameters such as short circuit current and generation rate.
Data Analysis and Visualization
After the simulation, analyze and visualize the data:
- Use script language to plot transmission, absorption, and reflection.
- Observe the generation rate, which is higher at the top surface compared to the bottom.
- Utilize the generated data files for further numerical analysis.
Conclusion
This session provided an overview of using Lumerical FDTD for simulating solar cells. By configuring the geometry, materials, and simulation parameters, we can effectively analyze the performance of solar cell designs.
Solar Cells Simulation Using Lumerical Tools (Part 2 - Lumerical FDTD) So, let's open Numerical FDTD. If I open a solar cell example, this is Numerical FDTD. Let's start with the waveguide. For the Numerical FDTD, you can define your structure by this item.
We can put triangular, rectangular, and other waveguides. For instance, if I want to put just a circle waveguide, a circle is added in the window, and you can change the geometry, X and Y, or radius, or the material, or other parameters here. Let's start with just a solar cell example.
I will delete this one. For the solar cell, we need a base. I will enable the base. The base is a X-span, three micrometers. You can see the X-span in the X direction. The X-span is three micrometers, and the Y-span is 0.5 micrometers. The material is aluminum.
In the material, if I select aluminum, and go to the material explorer, I can see the refractive index versus wavelength. The refractive index is around 1.1 for a wavelength of 0.8 micrometers. Next, I will select enable silicon.
The X is the same as the base, but the Y is larger, around three micrometers. The material is silicon. The refractive index of silicon is around 3.5 for a wavelength of 0.8 micrometers. Now, we define our structure. The next step is to select our solver.
We are simulating just a 2D simulation and the material. For the background, I put the background as one. Regarding the geometry, I simulate 0.5 micrometers in X and five micrometers in Y. In the mesh setting, we select auto non-uniform and conformal variant zero because it's a metal.
In the boundary condition, for the X case, this minimum boundary condition is periodic, but for the Y max is the PML. The PML absorbs the light. Now, our solver is selected. Next, we select our source. We are working on a solar cell, so the source is a plane wave.
The injection is in the Y direction. If for instance, I select forward, the light goes up, so I select backflow. For the range of frequency, 0.3 to 1.1 is enough for our case. Now, we need a monitor. For the monitor, we want to simulate type of all and seven wavelengths range.
The geometry is a linear monitor, linear X. I want to record these data. We predict that the t value is 0 because the blue is 0.3 and the t value is 0. 3. This is the geometry that you see is the base, a metal, and we cannot see any light after the middle.
This isn't t zero, and this is a reflection of the reflection monitor. In the solar generation, we can calculate the generation rate that I described in my presentation. This is a power trainer ah uh g export and the q export.
We can calculate absorption, thermal floor circuit generation, and these parameters. After we finish the simulation, we can see the short circuit is 28.3699 mA per cm 2. And also, we can see the maximum generation rate and other parameters.
Regarding to these values, we select the period as 18. The length of our device is around 9 micrometers. We can see the generation rate. The top of the surface is larger than the bottom. We can see the pet inverts option and some thermal. We can see the top all the surfaces, much of that. Yeah.
And also, we can see the risk environment. We can plot the transmission, absorption, and reflection. If I run this script, I can see a plot that shows me the transmission, reflection, and absorption.
