Solar Cell Detailed Balance Calculator

1. Overview

This software calculates the detailed balance limit for photovoltaic (PV) materials, incorporating various loss mechanisms such as thermalization, transmission, radiative, and Auger recombination losses. It provides key solar cell parameters, including efficiency, short-circuit current density (J_sc), open-circuit voltage (V_oc), and fill factor (FF), as functions of the bandgap energy.

The software also includes a graphical user interface for ease of use, allowing users to input parameters, visualize results, and export data.

2. Functionalities

a. Calculation of Solar Cell Parameters

• Computes:

  • Efficiency vs. bandgap

  • J_sc, V_oc, and FF vs. bandgap

  • Energy loss contributions (thermalization, transmission, radiative recombination, Auger recombination)

b. J-V Curve Plotting

• Allows plotting of the current density vs. voltage (J-V) curve for a specified bandgap.

• Supports user-defined voltage range.

• Data can be exported as a CSV file.

c. Spectrum Handling

• Users can load external spectral data for illumination conditions.

• The software processes and converts spectral data for use in calculations.

d. Adjustable Loss Parameters

• Includes input fields for:

  • Temperature (default: 300 K)

  • Series resistance (Rs) and shunt resistance (Rsh)

  • Auger recombination coefficients for electrons and holes

  • Injection factor (logarithmic scale control for light intensity scaling)

3. How to Use

a. Input Parameters

1. Load Spectrum File

   • Click the Browse button to select a spectral file (TXT format with two columns: wavelength [nm] and power density [W/m²/nm]).

2. Set Environmental and Material Parameters

   • Enter values for temperature, resistance, and Auger recombination coefficients.

   • Use the slider to adjust the injection factor.

3. Compute Detailed Balance Results

   • Click Calculate to generate efficiency and loss plots.

   • Results will be displayed in a text box.

b. Generate and Export J-V Curve

1. Enter Bandgap and Voltage Range

   • Specify the bandgap value in eV.

   • Define the minimum and maximum voltage range for the plot.

2. Plot J-V Curve

   • Click Plot J-V Curve to generate the graph.

3. Export J-V Data

   • Click Export Data to save the J-V data as a CSV file.

4. Limitations

a. Ideal Assumptions

• The software uses the Shockley-Queisser (SQ) limit, which assumes:

  • Perfect light absorption above the bandgap.

  • No non-radiative recombination (except for Auger recombination if enabled).

  • A step-function absorption profile.

• Deviation from experimental values is expected in real-world conditions due to defects, surface recombination, and non-ideal carrier transport.

b. Spectrum Format

• Input spectral data must be formatted correctly (two-column format with wavelength in nm and power density in W/m²/nm).

c. Computation Limits

• The solver may fail for extreme parameter values (e.g., very high Rs or Rsh).

• The J-V solver may not converge for unrealistic voltage ranges.

5. Output Files

a. Efficiency and Loss Data

• Automatically saves efficiency and loss calculations in solar_cell_data.txt.

• The file includes:

  • Bandgap energy

  • Thermalization loss

  • Transmission loss

  • Radiative recombination loss

  • Auger recombination loss

  • Converted energy (efficiency)

  • J_sc, V_oc, FF

b. J-V Data (If Exported)

• Saved in CSV format with two columns: Voltage (V) and Current Density (mA/cm²).

Citing This Software

When using results in academic or professional work, please cite the original detailed balance methodology and reference this calculator with its DOI.

Contact and Support

For technical support, feature requests, or reporting issues, please contact Zacharie Jehl Li-Kao:  zacharie.jehl@upc.edu

This description was generated by Claude AI.