The impact of cell design on light induced degradation in p-type silicon solar cells

Light-induced degradation (LID) in boron-doped Cz Si cells is known to be a function of the substrate boron and oxygen concentrations. In this paper, a combination of PC1D simulations and device theory is used to show that the efficiency loss due to LID is also a function of cell design. In particular, this loss was found to increase significantly when the surface passivation of cells is improved. The simulation data was also used to establish an empirical relationship which predicts the worst-case stabilized efficiency for boron-doped p-type Cz cells given only the initial efficiencies and thus provides a method for estimating the `efficiency parity' thresholds between n- and p-base cells. When combined with cost modeling, these findings have two practical implications - 1) it will be a challenge to achieve wide-spread grid-parity using current industrial cell processing techniques and substrates and, 2) n-type Si cells, which do not suffer from LID, will achieve efficiency-parity with the best p-type cells at much lower starting efficiencies. Consequently, n-type cells fabricated with low-cost/industrial technologies represent a potentially simpler route to grid-parity.