Probing the diffusion of excitons in 2D perovskites using optical microscopy.
Géraud Delport a, Samuel D Stranks a
a Optoelectronics Group, Cavendish Laboratory, University of Cambridge, UK., J.J. Thomson Avenue, Cambridge, United Kingdom
nanoGe Perovskite Conferences
Proceedings of International Conference on Perovskite Thin Film Photovoltaics and Perovskite Photonics and Optoelectronics (NIPHO20)
Sevilla, Spain, 2020 February 23rd - 25th
Organizer: Hernán Míguez
Oral, Géraud Delport, presentation 063
Publication date: 25th November 2019

Ruddlesden-Popper 2D Hybrid Organic perovskites (HOP) have remarkable excitonic properties that could be exploited in new generation devices such LEDs or polaritonic lasers or photovoltaic devices. Yet, the interplay between their structural and the optoelectronic properties are not fully understood. In particular, the ability of excitons to diffuse within this ultrathin quantum well structure is not fully understood [1].

In this work, we study the diffusion of carriers in 2D perovskites single crystals. We employed a time resolved photoluminescence (TR-PL) microscopy technique [2] that allows to monitor local variations of the excitonic diffusion.  We highlight the influence of the local structure (including the thickness of the quantum well) and the impact of traps on the diffusion coefficient and the diffusion lengths. If the obtained diffusion coefficients are smaller than in 3D perovskites, they are still relatively large compared to other excitonic materials. To understand the influence of traps in details, we study the changes in diffusion behaviour upon different excitation densities or operating conditions (gas,temperature…). This work provides a better understanding about the chemical and physical factors that still limit the diffusion of carriers in these 2D HOP materials. This study will provide insight to further improve HOP materials and devices performances.

References:

1) G. Delport et al. JPCL, 2019, 10 (17), 5153-5159

2) C. Stravrakas. G Delport et al. , submitted, arXiv:1909.13110 

 

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