Modelling of photo- and electroluminescence of hydrogenated microcrystalline silicon solar cells

Photoluminescence (PL) and electroluminescence (EL) have received much attention as characterization techniques for photovoltaic devices. The methods are applied to study e. g. optical band-gap, defect states, or quasi-Fermi level splitting. Spatially resolved EL imaging is used to derive local junction voltage differences making it a fast inline characterization method for solar modules. However, the interpretation of EL and PL experiments on hydrogenated microcrystalline silicon (mu c-Si:H) solar cells is more complex hampering the direct determination of local voltage differences. In this work we integrated an existing model for PL of mu c-Si:H silicon with a commercial device simulator for thin-film silicon devices. This way we extended the existing model from a spatially zero dimensional model to a one dimensional model which can also model EL. Furthermore the connection with an electrical device simulator enables the consistent modeling of EL, PL, and the electrical properties of the device. We compared experimental and simulation results for EL, PL and dark-, and illuminated-current/voltage characteristics over a wide temperature range (80 - 300 K). The simulations and experiments are in good agreement in the temperature range from 170 K up to room temperature. In experiments we observed several effects which cannot be explained in the previous zero dimensional model. (C) 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim