Effects of metallic contaminant type and concentration on photovoltaic performance degradation of p-type silicon solar cells

Abstract

We investigated the effects of the metallic contaminant type and concentration (Al, Cu, Ni, and Fe) on the minority-carrier recombination lifetime and photovoltaic performance degradation of p-type silicon solar cells. For all contaminants, the lifetime after annealing at 900 A degrees C for 15 min decreased with increasing concentration. The sequence of higher lifetime degradation induced by metallic contamination was Al (highest), Cu, Ni, and Fe (lowest), mainly determined by causing the diffusivity length and the solubility of the metallic contaminant in silicon. The sequence of higher lifetime degradation sensitivity induced by metallic contamination was Fe, Ni, Cu, and Al, as mainly determined by the trap energy level of the metallic contaminant in silicon. The contamination degraded the power-conversion efficiency (PCE) due to both the short-circuit-current and the fill-factor degradation. The degree and sensitivity of the PCE degradation depended on the contaminant type and concentration. The degree was the highest for Al, followed by Cu, Ni, and Fe, while the sensitivity was the highest for Fe, followed by Ni, Cu, and Al.