Quasi-3D Modelling of Concentrating Photovoltaic Solar Cell and Light Emitting Diode Front Contact Grid

Photovoltaic concentrating cells (CPV) and light emitting devices (LED) present analogous problems in the optimization of the front contact metal grid. In fact, both devices have to manage high current densities, can present similar semiconductor structures based on III-V compounds, have small dimensions and similar manufacturing process. In both cases, devices efficiencies maybe dramatically affected by front grid design, by operative conditions and even by fabrication defects, while a well optimized front grid could minimize the effects of imperfection in the device or assembly realization. A distributed network Quasi-3D model based on LT-Spice platform ((GREAT: Grid high-Resolution Electrical Analysis Tool)) has been implemented. Assuming that the device is constituted by three main horizontal planes: topmost grid layer, emitter layer and substrate layer, the model is able to simulate the electrical behavior of CPV and LED devices with metal front grids, with spatial resolution in the micrometer range. Different grid geometries and shapes have been compared, in order to: (I) optimize device efficiency, (II) minimize the impact on photovoltaic performances of non-uniform illumination of the CPV cell, (III) mitigate the effect of accidental grid finger interruption on current distribution in both CPV and LED devices.