Long-Range Strain in Lead Halide Perovskite Single Crystals

Strain plays a crucial role in semiconductor materials, often arising from heterointerfaces that involve materials with mismatched lattice parameters or thermal expansion coefficients. As a result, homogeneous single crystals are generally presumed to be strain-free. Contrary to this conventional belief, our study unveils the presence of long-range strain in free-standing lead halide perovskite single crystals. Remarkably, we have observed that spatial temperature inhomogeneity in the solution during crystal growth, induced by processes such as seeding or temperature ramping, leads to the development of long-range and residual strain within these single crystals. Such a strain is found to impact the band gap and carrier mobility of perovskite single crystals. This discovery challenges existing perceptions and introduces a new perspective for understanding and designing the physical and optoelectronic properties of perovskite single-crystalline devices, particularly in applications such as radiation detectors.