A simple model for voltage-dependent carrier collection efficiency in solar cells

作者：McCarthy R F; Hillhouse H W^*

来源：Journal of Applied Physics, 2014, 115(14): 143703.

DOI：10.1063/1.4870827

Here, we present a simple, yet powerful model developed to calculate collection efficiencies for photogenerated charge carriers in semiconductor devices. In the model, we define a new collection length, which is calculated using transit times that depend on both drift and diffusion for charge collection. The model accounts for a non-uniform electric field determined by the depletion approximation. The voltage-dependence of the photocurrent can be calculated using appropriate given photogeneration rate, and our results were found to match very closely with those calculated using a finite difference solution of the full device equations. The transit time model reported here leads to fully analytical equations for the collection length. They allow one to quickly explore wide ranges of parameters including mobility, minority carrier lifetime, and device thickness. The simplicity of this model allows it to be applied to other devices architectures as well. In fact, the motivating factor to develop the model was to quickly illuminate the advantages and disadvantages of various device designs, from nanostructured photovoltaics to light trapping strategies, and plasmonic enhancements.

• 出版日期2014-4-14