Two-dimensional lead halide perovskites are promising candidates for optoelectronic and photovoltaic applications because of their strongly bound excitons and enhanced stabilities. This work investigates how tuning the quantum well thickness can control the charge and energy transfer phenomena occurring across the hybrid interface in a 2D perovskite with pyrene molecular ligands, C16H10-(CH2)4-NH3+, demonstrating diverse excitonic states with distinct properties. We show that the n=1 perovskite undergoes efficient triplet energy transfer from the inorganic layer to the organic cation, possibly through a tunneling mechanism in the Marcus inverted regime. This leads to an extremely rapid triplet energy transfer process with a time constant &lt; 100 ps that is largely temperature independent. The n=2 perovskite, however, shows no such triplet emission. Instead, its type II band-alignment supports the formation of very long-lived and mobile interlayer charge transfer excitons (CTEs) at low temperatures. These findings pave the way for further exploration of how band engineering in perovskites can allow us to control the various energy and charge transfer functionalities accessible in these hybrid 2D materials.

Controlling energy and charge transfer at the organic-inorganic interfaces of two dimensional perovskites

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ACS Fall 2022

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