Residual Strain Evolution Induced by Crystallization Kinetics During Anti‐Solvent Spin Coating in Organic–Inorganic Hybrid Perovskite

Abstract

Organic–inorganic hybrid perovskite (OIHP) polycrystalline thin films are attractive due to their outstanding photoelectronic properties. The anti‐solvent spin coating method is the most widely used to synthesize these thin films, and the residual strain is inevitably originates and evolves during the process. However, this residual strain evolution induced by crystallization kinetics is still poorly understood. In this work, the in situ and ex situ synchrotron grazing‐incidence wide‐angle X‐ray scattering (GIWAXS) are utilized to characterize the evolution and distribution of the residual strain in the OIHP polycrystalline thin film during the anti‐solvent spin coating process. A mechanical model is established and the mechanism of the crystallization kinetics‐induced residual strain evolution process is discussed. This work reveals a comprehensive understanding of the residual strain evolution during the anti‐solvent spin coating process in the OIHP polycrystalline thin films and provides important guidelines for the residual strain‐related strain engineering, morphology control, and performance enhancement.

In situ Stress Monitoring Reveals Tension and Wrinkling Evolutions during Halide Perovskite Film Formation

“…In fact, recent in situ investigation has provided evidence that wrinkling can occur during solution processing of hybrid perovskites. 25 Complex compositional engineering has been deployed to achieve smooth film 26 and mitigate wrinkling, 18,19 but changing the composition, even by small amounts, can have significant consequences on the semiconductor properties of the MHP, such as its bandgap, as well as its defect chemistry and stability. 27 It is therefore imperative to understand the origins of stress formation in solution-processed MHP films, which will then allow the development of effective stress engineering strategies to mitigate wrinkling in perovskite films that have the optimal thickness for absorbing light.…”

“…With modern perovskite compositions, solution-to-solid phase transformation is often initiated with an antisolvent drip − and proceeds during solution processing, which significantly increases the likelihood that residual stress forms prior to thermal annealing. In fact, recent in situ investigation has provided evidence that wrinkling can occur during solution processing of hybrid perovskites . Complex compositional engineering has been deployed to achieve smooth film and mitigate wrinkling, , but changing the composition, even by small amounts, can have significant consequences on the semiconductor properties of the MHP, such as its bandgap, as well as its defect chemistry and stability .…”