Design constraints and guidelines for CdS/CdTe nanopillar based photovoltaics

The performance dependence of a CdS/CdTe nanopillar solar cell on various device and materials parameters is explored while examining its performance limits through detailed device modeling. The optimized cell enables efficiencies >∼20% with minimal short circuit current dependence on bulk minority carrier diffusion length, demonstrating the efficient collection of photogenerated carriers, therefore, lowering the materials quality and purity constraints. Given the large p-n junction interface area, the interface recombination velocity is shown to have detrimental effect on the device performance of nanopillar solar cells. In that regard, the CdS/CdTe material system is optimal due to its low interface recombination velocity.