Oceanography

Optics

Physics

Geology

Engineering

Philosophy

Aerospace engineering

Paleontology

Perovskite (structure)

Composite material

Nanotechnology

Organic chemistry

Chemistry

Thin film

Materials science

Surface energy

Stress (linguistics)

Pinhole (optics)

Substrate (aquarium)

Climb

Sediment

Linguistics

Chemical engineering

Phase (matter)

Morphology (biology)

Genetics

Deposition (geology)

Nanometre

Biology

ACS Energy Letters

Significant effort has focused on controlling the deposition of perovskite films to enable uniform films, enabling efficiencies to climb dramatically. However, little attention has been paid to the evolution of thin-film stresses during deposition and the consequent effect on film morphology. While a textured surface topology has potential benefits for light scattering, a smooth surface is desirable to enable the pinhole-free deposition of contact layers. We show that the highly textured morphology made by popular antisolvent conversion methods arises because of in-plane compressive stress experienced during the intermediate phase of film formation where the substrate constrains the film from expanding—leading to energy release in the form of wrinkling, resulting in trenches that can be hundreds of nanometers deep with periods of several micrometers. We demonstrate that the extent of wrinkling is correlated with the rate of film conversion and that ultrasmooth films are obtained by slowing the rate of film formation.

Controlling Thin-Film Stress and Wrinkling during Perovskite Film Formation