Stable Biexcitons In Two-Dimensional Metal-Halide Perovskites With Strong Dynamic Lattice Disorder

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Date
2018-03-08Author
Thouin, Félix
Neutzner, Stefanie
Cortecchia, Daniele
Dragomir, Vlad Alexandru
Soci, Cesare
Salim, Teddy
Lam, Yeng Ming
Leonelli, Richard
Petrozza, Annamaria
Kandada, Ajay Ram Srimath
Silva, Carlos
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Show full item recordAbstract
With strongly bound and stable excitons at room temperature, single-layer, two-dimensional organic-inorganic
hybrid perovskites are viable semiconductors for light-emitting quantum optoelectronics applications. In such
a technological context, it is imperative to comprehensively explore all the factors—chemical, electronic,
and structural—that govern strong multiexciton correlations. Here, by means of two-dimensional coherent
spectroscopy, we examine excitonic many-body effects in pure, single-layer (PEA)2PbI4 (PEA = phenylethylammonium).
We determine the binding energy of biexcitons—correlated two-electron, two-hole quasiparticles—to
be 44 ± 5meV at room temperature. The extraordinarily high values are similar to those reported in other strongly
excitonic two-dimensional materials such as transition-metal dichalcogenides. Importantly, we show that this
binding energy increases by ∼25% upon cooling to 5 K. Our work highlights the importance of multiexciton
correlations in this class of technologically promising, solution-processablematerials, in spite of the strong effects
of lattice fluctuations and dynamic disorder.