Mapping carrier transport in single-crystal 2D perovskite heterostructures
Gianluca Grimaldi a b, Alexander Sneyd a, Ivar Kotte b, Jaco Geuchies c, Bruno Ehrler b, Akshay Rao a
a Department of Physics, Cavendish Laboratory, University of Cambridge; Cambridge, UK
b AMOLF, Amsterdam, Netherlands, Netherlands
c Max Planck Institute for polymer Research, 55128 Mainz, Germany
International Conference on Hybrid and Organic Photovoltaics
Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV22)
València, Spain, 2022 May 19th - 25th
Organizers: Pablo Docampo, Eva Unger and Elizabeth Gibson
Poster, Gianluca Grimaldi, 255
Publication date: 20th April 2022

2D perovskites have emerged as a new class of materials for optoelectronic applications, providing facile solution-processing and enhanced air stability compared to bulk perovskites. Thanks to these beneficial properties, mixtures of 2D perovskite layers of different thickness, called 2D/3D perovskites, have been integrated successfully in high efficiency perovskite solar cells[1,2] and LEDs[3,4]. Despite their promises for efficient optoelectronic devices, understanding and optimizing charge transport across 2D/3D perovskite stacks remains challenging, as it is determined by an interplay of in-plane and out-of-plane diffusion and by transport at heterostructures formed by different 2D perovskite thicknesses.

Most of the characterization of transport in these systems has focused either on full device performance or on spectral- and time-resolved measurement of carrier population changes in the mixed 2D/3D films [4,5,6]. However, measurements on the distributions of different 2D perovskite thicknesses are affected by the relative prevalence of different thicknesses and by their spatial distribution. These factors hamper a precise assessment of the mechanism and dynamics of carrier transport through the building blocks of 2D/3D perovskite stacks, i.e. individual heterostructures between two layer of 2D perovskite with different thicknesses.

In our work, we construct heterostructures between single crystals of 2D perovskite with different layer thickness, and characterize the transport of photoexcited carriers across the heterostructures with Transient Absorption Microscopy and Photoluminescence microscopy techniques. From the evolution of the Transient Absorption signal on the heterostructure we obtain information on band alignment in the heterostructure and the extract the dynamics of carrier transfer. Furthermore, we observe the presence of a lower energy Transient Absorption bleach localized at the edges of individual 2D perovskite flakes, associated with strongly absorptive edge states. Our results shine light on the transport properties of 2D perovskite heterostructures, providing insights for the design and optimization of 2D/3D layers tailored for specific optoelectronic applications.

We use our own and third party cookies for analysing and measuring usage of our website to improve our services. If you continue browsing, we consider accepting its use. You can check our Cookies Policy in which you will also find how to configure your web browser for the use of cookies. More info