Modeling of Edge Recombination Losses in Half-Cells

33rd European Photovoltaic Solar Energy Conference and Exhibition; 853-856
A new approach to model the impact of edge recombination within silicon solar cells using a 3D simulation of the entire cell geometry within Quokka3 is presented. The contribution of edge recombination within the space charge region (SCR), which is not directly accounted for in Quokka3’s skin concept, is included by an effective property, a localized edge-length specific saturation current density with an ideality factor of 2: J02,edge. A worst-case value of 19 nA/cm was found to be largely invariable for varying device properties. The new model is applied to predict the worst-case influence of the cut-edge within PERC half-cells. A moderate efficiency loss of 0.1 %abs is predicted, for which the SCR and non-SCR edge recombination contribute non-additive. Differentiating those two loss mechanisms reveals a very similar impact on light-JV characteristics dominantly on pseudo-fill-factor, whereas only the SCR mechanism is visible in dark-JV curves as an increased J02. This means that non-SCR edge loss contributions will be missed by the commonly applied dark-J02 characterization approach. Dedicated experiments to reveal the different mechanisms by measuring front and rear laser-scribed half-cell designs before cleavage are carried out and compared to the simulations results.