Improving the Carrier Lifetime of Tin Sulfide via Prediction and Mitigation of Harmful Point Defects

Tin monosulfide (SnS) is an emerging
thin-film absorber material
for photovoltaics. An outstanding challenge is to improve carrier
lifetimes to >1 ns, which should enable >10% device efficiencies.
However, reported results to date have only demonstrated lifetimes
at or below 100 ps. In this study, we employ defect modeling to identify
the sulfur vacancy and defects from Fe, Co, and Mo as most recombination-active.
We attempt to minimize these defects in crystalline samples through
high-purity, sulfur-rich growth and experimentally improve lifetimes
to >3 ns, thus achieving our 1 ns goal. This framework may prove
effective
for unlocking the lifetime potential in other emerging thin-film materials
by rapidly identifying and mitigating lifetime-limiting point defects.