Abstract
Mixing iodide and bromide in halide perovskite semiconductors is an effective strategy to tune their band gap; therefore, mixed-halide perovskites hold great promise for color-tunable LEDs and tandem solar cells. However, the band gap of mixed-halide perovskites is unstable under (sun-)light, since the halides segregate into domains of different band gaps. Using pressure-dependent ultrafast transient absorption spectroscopy, we find that high external pressure increases the range of stable halide mixing ratios. Chemical compression, by inserting a smaller cation, has the same effect, which means that any iodide:bromide ratio can be stabilized by tuning the crystal volume and compressibility. We interpret these findings as an increased thermodynamic stabilization through alteration of the Gibbs free energy via the largely overlooked PΔV term.
| Original language | English |
|---|---|
| Article number | 100120 |
| Journal | Cell Reports Physical Science |
| Volume | 1 |
| Issue number | 8 |
| DOIs | |
| Publication status | Published - 2020 Aug 26 |
Bibliographical note
Funding Information:The work of E.M.H., L.A.M., F.W., J.V., L.M., H.J.B., and B.E. is part of the Dutch Research Council (NWO) and was performed at the research institute AMOLF. This research was also supported by the Creative Materials Discovery Program through the National Research Foundation of Korea (NRF), funded by the Ministry of Science and ICT ( 2018M3D1A1058536 ). We are grateful to the UK Materials and Molecular Modelling Hub for computational resources, which is partially funded by EPSRC ( EP/P020194/1 ). The authors thank Henk-Jan Boluijt for the design of Figure 1 A.
Funding Information:
The work of E.M.H. L.A.M. F.W. J.V. L.M. H.J.B. and B.E. is part of the Dutch Research Council (NWO) and was performed at the research institute AMOLF. This research was also supported by the Creative Materials Discovery Program through the National Research Foundation of Korea (NRF), funded by the Ministry of Science and ICT (2018M3D1A1058536). We are grateful to the UK Materials and Molecular Modelling Hub for computational resources, which is partially funded by EPSRC (EP/P020194/1). The authors thank Henk-Jan Boluijt for the design of Figure 1A. E.M.H. conceived the idea and performed the pressure-dependent TA experiments and data analysis together with L.A.M. under the supervision of B.E. F.W. performed the XRD and pressure-dependent UV-VIS measurements and assisted in the sample preparation together with L.M. J.V. assisted in the TA experiments under the supervision of H.J.B. Thermodynamic calculations were performed by A.W. Y.-W.W. and Y.-K.J. The manuscript was written by E.M.H. and A.W. with input from all of the other authors. The authors declare no competing interests.
Publisher Copyright:
© 2020 The Authors
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)
- Materials Science(all)
- Chemistry(all)
- Energy(all)
- Engineering(all)