Interlayer Charge Transfer in 2D Hybrid Perovskites Containing Electroactive Ligands towards Enhanced Charge Carrier Transport

The family of hybrid organic-inorganic lead-halide perovskites are the subject of intense interest for optoelectronic applications. Due to the electronically inert nature of most organic molecules, the inorganic sublattice generally dominates the electronic structure and therefore optoelectronic properties of perovskites. However, over the past years interest in the incorporation of electronically active organic cations has been increasing.[1] We use optically and electronically active carbazole-based Cz-C_i molecules [2-3], where C_i indicates an alkylammonium chain and i indicates the number of CH₂ units in the chain, varying from 3−5, as cations in the 2D perovskite structure (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. We measure 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. Electrical charge transport measurements using single-carrier devices show markedly increased out-of-plane carrier mobilities compared to (PEA)₂PbI₄, with carrier mobility increasing from i=5 to i=3.[4]<br/><br/>[1] Van Gompel, W.T.M.; Lutsen, L.; Vanderzande, D., Journal of Materials Chemistry C 2023, Advance Article (10.1039/D3TC02553E)<br/><br/>[2] Herckens, R.; Van Gompel, W. T. M.; Song, W. Y.; Gelvez-Rueda, M. C.; Maufort, A.; Ruttens, B.; D'Haen, J.; Grozema, F. C.; Aernouts, T.; Lutsen, L.; Vanderzande, D., Journal of Materials Chemistry A 2018, 6 (45), 22899-22908 (10.1039/c8ta08019d)<br/><br/>[3] Van Landeghem, M.; Van Gompel, W. T. M.; Herckens, R.; Lutsen, L.; Vanderzande, D.; Van Doorslaer, S.; Goovaerts, E., The Journal of Physical Chemistry C 2021, 125 (33), 18317-18327 (10.1021/acs.jpcc.1c05005)<br/><br/>[4] Boeije, Y.; Van Gompel, W. T. M.; Zhang, Y.; Ghosh, P.; Zelewski, S.; Maufort, A.; Roose, B.; Ying Ooi, Z.; Chowdhury, R.; Devroey, I.; Lenaers, S.; Tew, A.; Dai, L.; Dey, K.; Salway, H.; Friend, R. H.; Sirringhaus, H.; Lutsen, L.; Vanderzande, D.; Rao, A.; Stranks, S. D., Journal of the American Chemical Society 2023, Just Accepted (10.1021/jacs.3c05974)