Probing the Photodynamics of (Micropatterned) Quasi-2D Metal Halide Perovskites
Lisanne Einhaus a, Xiao Zhang b, Annemarie Huijser a, André ten Elshof b
a Photocatalytic Synthesis (PCS) Group, Faculty of Science and Technology, MESA+ Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE Enschede, Netherlands
b Inorganic Materials Science (IMS) Group, Faculty of Science and Technology, MESA+ Institute for Nanotechnology, University of Twente
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, Lisanne Einhaus, 252
Publication date: 20th April 2022

Metal halide perovskites (MHPs) have gained significant interest as photovoltaic materials due to their impressive optoelectronic properties: high absorption coefficient, tunable bandgap and long charge carrier lifetimes. The power conversion efficiency has dramatically increased from 3.8% to over 25% [1] over the past few years. However, the main challenge for application is the long-term stability under operating conditions.

This issue is mitigated in two-dimensional (2D) lead-halide perovskites. Instead of the commonly used small cations such as methylammonium in the 3D analogues, the 2D perovskites consist of inorganic octahedral lead-halide layers separated by large organic cations. However, here the electrons and holes are spatially confined to the conducting inorganic layer, leading to detrimental quantum confinement effects. By increasing the inorganic layer thickness in between the large organic cations, quasi-2D structures are formed, the so-called Ruddlesden-Popper or Dion-Jacobson phases. In this way, high efficiency and stability properties are combined [2].

The mechanistic understanding of the relation between the MHP microstructure and the optoelectronic properties is still in an early stage. We aim to explore the photodynamics of quasi-2D perovskite layers with various microstructures, by time-resolved photoluminescence spectroscopy (TRPL) and ultrafast transient absorption (TA). While TRPL only detects emissive processes, TA is also capable of probing non-emissive excited-state processes in a femtosecond-nanosecond time window, such as hot carrier cooling, excited state processes, charge transport etc. This provides unique insights into the band structure and the photodynamical processes of the films, and can be used to further improve these materials.

We use these techniques to study micropatterned perovskite films with mm sized structures. According to previous work of Kamminga et. al., the patterning process improves the overall crystallization of the perovskite film and increases the grain sizes compared to nonpatterned films [3]. Hence, the optoelectronic properties can be expected to improve as well. We explore, for the first time, the effects of micropatterning on the photodynamics of quasi-2D perovskite films.

We thank the NWO TTW program for funding our project (17711). We also thank the user committee associated with this project, consisting of Solliance, Fraunhofer Institute for Solar Energy Systems ISE, Morphotonics and Domicro, for their support and stimulating scientific discussions. 

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