External Quantum Efficiency (EQE) is defined as the ratio of number of charge carriers collected at the electrode to the number of photons incident on the solar cell. Low EQE can be attributed to several optical and electrical loss mechanism for charge carriers such as:

1.) The absorber layer is too thin and does not absorb all of the photons.
2.) Photons are not absorbed as they may have energy smaller than the bandgap.
3.) Photons can be reflected back from the solar cell.
4.) Parasitic absorption losses in the inactive layers of the cell. 
5.) Recombination of light excited charge carriers before they are collected at the contacts.

J_sc is an important performance parameter to study solar cells of all available technologies. Calculating this requires a lot of effort as interpolation (for matching EQE data with AM 1.5G spectra) and integration are to be performed with precision. To calculate short circuit current density (J_sc), EQE measurement is performed under short circuit conditions. Since J_sc can be also calculated fom JV measurement, EQE holds the advantage of independent spectral shape of light source and is also independent of cell area. For J_sc calculation photon flux is multiplied with EQE, leading to the flow of electrons leaving the solar cell at corresponding wavelength. If we integrate  (photon flux * EQE) throughout the wavelength range J_sc is obtained. For crystalline silicon, the important range would be from 300 to 1200 nm.
 

Researchers should cite this work as follows:

• Prateek Malhotra, Dr. Subhyan Biswas, Ganesh D Sharma (2021), "Calculating short circuit current density (Jsc) from external quantum efficiency (EQE)," https://nanohub.org/resources/jscfromeqe. (DOI: 10.21981/XY24-RV08).

  BibTex | EndNote

1. external quantum efficiency
2. solar cells
3. solar energy