Abstract
We demonstrate the formation of large sheets of layered organic-inorganic perovskite (OIPC) crystals, as thin as a single unit cell, prepared by mechanical exfoliation. The resulting two-dimensional OIPC nanosheets of 2.4 nm thickness are direct semiconductors with an optical band gap of 2.4 eV. They exhibit unusually strong light-matter interaction with an optical absorption as high as 25% at the main excitonic resonance, as well as bright photoluminescence. We extract an exciton binding energy of 490 meV from measurement of the series of excited exciton states. The properties of the excitons are shown to be strongly influenced by the changes in the dielectric surroundings. The environmental sensitivity of these ultrathin OIPC sheets is further reflected in the strong suppression of a thermally driven phase transition present in the bulk crystals.
| Original language | English |
|---|---|
| Article number | 045414 |
| Number of pages | 7 |
| Journal | Physical Review B |
| Volume | 92 |
| Issue number | 4 |
| DOIs | |
| Publication status | Published - 15 Jul 2015 |
| Externally published | Yes |
Funding
This work was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, with funding at Columbia University through the Energy Frontier Research Center under Grant No. DE-SC0001085 and at SLAC National Accelerator Laboratory through the AMOS program within the Chemical Sciences, Geosciences, and Biosciences Division. O.Y. acknowledges funding by the FP7 People program under the project Marie Curie IOF-622653. We also acknowledge support from the Keck Foundation and from Alexander von Humboldt Foundation for funding a Feodor Lynen Fellowship for A.C. The authors thank David Mitzi, David Cahen, Saar Kirmayer, and Louis Brus for fruitful discussions. O.Y. and A.C. contributed equally to this work.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics