Relating Surface Photovoltage to IQE for Contactless In-Situ IQE Monitoring

We derive a simple approximation relating surface photovoltage to IQE based on the non-ideal diode equation. Surface photovoltage and IQE spectra are generated in the SCAPS-1D Poisson Drift Diffusion solver, showing that this approximation reliably transforms IQE to SPV and vice versa in many cases. Exceptional cases, arising from the creation of a secondary depletion region by band misalignment or Fermi-level pinning are explored.