loading page

Mapping Losses Through Empirical Extraction of the Spatial External Luminescence Efficiency
  • Tamir Yeshurun,
  • Mor Fiegenbaum-Raz,
  • Gideon Segev
Tamir Yeshurun
Tel Aviv University School of Electrical Engineering
Author Profile
Mor Fiegenbaum-Raz
Tel Aviv University School of Electrical Engineering
Author Profile
Gideon Segev
Tel Aviv University School of Electrical Engineering

Corresponding Author:[email protected]

Author Profile

Abstract

The performance of photovoltaic cells is determined by the transport and loss mechanisms within the cells. Thus, quantitative assessment of these mechanisms is fundamental for device optimization and the evaluation of new materials and interfaces. In this work we introduce a new method for in-depth quantitative mapping of loss and charge transport mechanisms under operando conditions. The spatial external luminescence efficiency (SELE) is defined as the probability for an electron-hole pair that is photo-generated at a specific depth within a device, to contribute to photoluminescence. By coupling incident wavelength-dependent external luminescence efficiency measurements with optical modeling, we demonstrate the extraction of the SELE of a GaAs wafer. The SELE directly maps the competition between radiative and non-radiative recombination within the device and can thus be used to study the properties of surfaces and interfaces. Moreover, since the external luminescence efficiency is related to the obtainable photo-voltage from the device, the SELE can be used to map the spatial contribution to the device photo-voltage. The SELE is also calculated using device simulations that account for charge transport and photon recycling. These simulations validate the extraction method and attribute features in the SELE profile to important physical quantities such as the surface recombination velocity and carrier lifetime.