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Optical Investigation of Broadband White-Light Emission in Self-Assembled Organic–Inorganic Perovskite (C 6 H 11 NH 3 ) 2 PbBr 4

2015; American Chemical Society; Volume: 119; Issue: 41 Linguagem: Inglês

10.1021/acs.jpcc.5b06211

1932-7455

Aymen Yangui, Damien Garrot, Jean‐Sébastien Lauret, A. Lusson, Guillaume Bouchez, Emmanuelle Deleporte, Sébastien Pillet, El‐Eulmi Bendeif, Miguel Castro, Smaı̈l Triki, Y. Abid, Kamel Boukheddaden,

Solid-state spectroscopy and crystallography

The performance of hybrid organic perovskite (HOP) for solar energy conversion is driving a renewed interest in their light emitting properties. The recent observation of broad visible emission in layered HOP highlights their potential as white-light emitters. Improvement of the efficiency of the material requires a better understanding of its photophysical properties. We present in-depth experimental investigations of white-light (WL) emission in thin films of the (C6H11NH3)2PbBr4. The broadband, strongly Stokes shifted emission presents a maximum at 90 K when excited at 3.815 eV, and below this temperature coexists with an excitonic edge emission. X-rays and calorimetry measurements exclude the existence of a phase transition as an origin of the thermal behavior of the WL luminescence. The free excitonic emission quenches at low temperature, despite a binding energy estimated to 280 meV. Time-resolved photoluminescence spectroscopy reveals the multicomponent nature of the broad emission. We analyzed the dependence of these components as a function of temperature and excitation energy. The results are consistent with the existence of self-trapped states. The quenching of the free exciton and the thermal evolution of the WL luminescence decay time are explained by the existence of an energy barrier against self-trapping, estimated to ∼10 meV.