Analysis of Temperature Dependent Characteristics of Diffused Regions in Silicon Solar Cells

To maximize the annual energy output of silicon based photovoltaic modules beyond standard testing conditions (STC), it is important to assess temperature dependent device properties of silicon solar cells. In this study we characterize the temperature dependence of the dark saturation current density J
₀
of diffused regions (e.g. emitter layers). In particular, we test whether the theoretical first-order approximation of J
₀
/n
_i
²
being temperature independent holds. For this, the lifetime of symmetrically diffused silicon samples with varying dopant types and profiles is measured by temperature dependent modulated photoluminescence to extract J
₀
as a function of injection and temperature. We find that for passivated diffused regions J
₀
/n
_i
²
shows a temperature coefficient in the range of -0.5 to -0.7 %/K, while even lower coefficients and more scattering is observed for the unpassivated samples. The presented data and approach can be used to improve the beyond-STC predictive power of device simulations which use J
₀
inputs.