Experimental Evidence for Defect Tolerance in Pb-Halide Perovskites

TL;DR

This study provides the first direct experimental evidence that lead-halide perovskites exhibit defect tolerance, meaning their optoelectronic properties are unaffected by structural defects, which is crucial for their device performance.

Contribution

It offers the first direct bulk evidence of defect tolerance in Pb-Halide Perovskites using high-sensitivity methods, advancing understanding of their intrinsic properties.

Findings

Defect tolerance observed in 3D, 2D-3D, and 2D Pb-HaPs.

Bulk measurements confirm defect tolerance beyond surface effects.

Results support defect tolerance as a key factor in perovskite performance.

Abstract

The term defect tolerance (DT) is used often to rationalize the exceptional optoelectronic properties of Halide Perovskites (HaPs) and their devices. Even though DT lacked direct experimental evidence, it became a "fact" in the field. DT in semiconductors implies that structural defects do not translate to electrical and optical effects (e.g., due to charge trapping), associated with such defects. We present the first direct experimental evidence for DT in Pb-HaPs by comparing the structural quality of 2-dimensional (2D), 2D-3D, and 3D Pb-iodide HaP crystals with their optoelectronic characteristics using high-sensitivity methods. Importantly, we get information from the materials' bulk, because we sample at least a few hundred nanometers, up to several micrometers, from the sample's surface, which allows for assessing intrinsic bulk (and not only surface-) properties of HaPs. The results point to DT in 3D, 2D-3D, and 2D Pb-HaPs. Overall, our data provide an experimental basis to rationalize DT in Pb-HaPs. These experiments and findings can guide the search for, and design of other materials with DT.