Tailoring Interlayer Charge Transfer Dynamics in 2D Perovskites with Electroactive Spacer Molecules

Yorrick Boeije; Wouter T M Van Gompel; Youcheng Zhang; Pratyush Ghosh; Szymon J Zelewski; Arthur Maufort; Bart Roose; Zher Ying Ooi; Rituparno Chowdhury; Ilan Devroey; Stijn Lenaers; Alasdair Tew; Linjie Dai; Krishanu Dey; Hayden Salway; Richard H Friend; Henning Sirringhaus; Laurence Lutsen; Dirk Vanderzande; Akshay Rao; Samuel D Stranks

doi:10.1021/jacs.3c05974

Tailoring Interlayer Charge Transfer Dynamics in 2D Perovskites with Electroactive Spacer Molecules

J Am Chem Soc. 2023 Oct 4;145(39):21330-21343. doi: 10.1021/jacs.3c05974. Epub 2023 Sep 22.

Authors

Yorrick Boeije^{1

2}, Wouter T M Van Gompel³, Youcheng Zhang^{2

4}, Pratyush Ghosh², Szymon J Zelewski^{1

2

5}, Arthur Maufort³, Bart Roose¹, Zher Ying Ooi¹, Rituparno Chowdhury², Ilan Devroey³, Stijn Lenaers³, Alasdair Tew², Linjie Dai^{1

2}, Krishanu Dey², Hayden Salway¹, Richard H Friend², Henning Sirringhaus², Laurence Lutsen³, Dirk Vanderzande³, Akshay Rao², Samuel D Stranks^{1

2}

Affiliations

¹ Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge CB3 0AS, U.K.
² Department of Physics, Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, U.K.
³ Institute for Materials Research (IMO-IMOMEC), Hybrid Materials Design (HyMaD), Hasselt University, Martelarenlaan 42, B-3500 Hasselt, Belgium.
⁴ Cambridge Graphene Centre, Department of Engineering, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0FA, U.K.
⁵ Department of Semiconductor Materials Engineering, Faculty of Fundamental Problems of Technology, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland.

Abstract

The family of hybrid organic-inorganic lead-halide perovskites are the subject of intense interest for optoelectronic applications, from light-emitting diodes to photovoltaics to X-ray detectors. Due to the inert nature of most organic molecules, the inorganic sublattice generally dominates the electronic structure and therefore the optoelectronic properties of perovskites. Here, we use optically and electronically active carbazole-based Cz-C_i molecules, where C_i indicates an alkylammonium chain and i indicates the number of CH₂ units in the chain, varying from 3 to 5, as cations in the two-dimensional (2D) perovskite structure. By investigating the photophysics and charge transport characteristics of (Cz-C_i)₂PbI₄, we demonstrate a tunable electronic coupling between the inorganic lead-halide and organic layers. The strongest interlayer electronic coupling was found for (Cz-C₃)₂PbI₄, where photothermal deflection spectroscopy results remarkably reveal an organic-inorganic charge transfer state. Ultrafast transient absorption spectroscopy measurements demonstrate ultrafast hole transfer from the photoexcited lead-halide layer to the Cz-C_i molecules, the efficiency of which increases by varying the chain length from i = 5 to i = 3. The charge transfer results in long-lived carriers (10-100 ns) and quenched emission, in stark contrast to the fast (sub-ns) and efficient radiative decay of bound excitons in the more conventional 2D perovskite (PEA)₂PbI₄, in which phenylethylammonium (PEA) acts as an inert spacer. Electrical charge transport measurements further support enhanced interlayer coupling, showing increased out-of-plane carrier mobility from i = 5 to i = 3. This study paves the way for the rational design of 2D perovskites with combined inorganic-organic electronic properties through the wide range of functionalities available in the world of organics.