Abstract
Strain engineering is a powerful tool with which to enhance semiconductor device performance1,2. Halide perovskites have shown great promise in device applications owing to their remarkable electronic and optoelectronic properties3-5. Although applying strain to halide perovskites has been frequently attempted, including using hydrostatic pressurization6-8, electrostriction9, annealing10-12, van der Waals force13, thermal expansion mismatch14, and heat-induced substrate phase transition15, the controllable and device-compatible strain engineering of halide perovskites by chemical epitaxy remains a challenge, owing to the absence of suitable lattice-mismatched epitaxial substrates. Here we report the strained epitaxial growth of halide perovskite single-crystal thin films on lattice-mismatched halide perovskite substrates. We investigated strain engineering of α-formamidinium lead iodide (α-FAPbI3) using both experimental techniques and theoretical calculations. By tailoring the substrate composition-and therefore its lattice parameter-a compressive strain as high as 2.4 per cent is applied to the epitaxial α-FAPbI3 thin film. We demonstrate that this strain effectively changes the crystal structure, reduces the bandgap and increases the hole mobility of α-FAPbI3. Strained epitaxy is also shown to have a substantial stabilization effect on the α-FAPbI3 phase owing to the synergistic effects of epitaxial stabilization and strain neutralization. As an example, strain engineering is applied to enhance the performance of an α-FAPbI3-based photodetector.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 209-215 |
| Number of pages | 7 |
| Journal | Nature |
| Volume | 577 |
| Issue number | 7789 |
| DOIs | |
| State | Published - Jan 8 2020 |
Bibliographical note
KAUST Repository Item: Exported on 2020-10-01Acknowledgements: We thank T. N. Ng and Z. Wu for guidance on the transient photocurrent measurement; P. Liu and S. Yu for sharing the Rikagu Smartlab diffractometer; D. P. Fenning and X. Li for discussions; Q. Lin for guidance on the reciprocal space mapping measurements; S. Wang for analysis and discussions of the UPS; Y. Zeng for training on the Renishaw inVia Raman spectrometer; Y. Li, Y. Yin and M. Chen for guidance on the finite element analysis simulations; and S. Xiang for constructive feedback on manuscript preparation. This work was supported by the startup fund by the University of California San Diego. The microfabrication involved in this work was performed at the San Diego Nanotechnology Infrastructure (SDNI) of UCSD, a member of the National Nanotechnology Coordinated Infrastructure, which was supported by the the National Science Foundation (grant number ECCS-1542148). K.Y. acknowledges the National Science Foundation under award number ACI-1550404 and computational resources from Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation grant number ACI-1548562.