Ultrafast Vibrational Control of Hybrid Perovskite Devices Reveals the Influence of the Organic Cation on Electronic Dynamics

TL;DR

This study demonstrates ultrafast vibrational control of hybrid perovskite solar cells, showing how organic cation vibrations influence electronic dynamics and could improve photovoltaic efficiency.

Contribution

It introduces the first demonstration of vibrational control in perovskite devices, revealing the role of organic cation vibrations in electronic coupling and device performance.

Findings

Ultrafast vibrational control achieved within ~300 fs.

Hydrogen bonds mediate coupling between cation and inorganic lattice.

Cation dynamics may reduce non-radiative recombination in perovskites.

Abstract

Vibrational control (VC) of photochemistry through the optical stimulation of structural dynamics is a nascent concept only recently demonstrated for model molecules in solution. Extending VC to state-of-the-art materials may lead to new applications and improved performance for optoelectronic devices. Metal halide perovskites are promising targets for VC due to their mechanical softness and the rich array of vibrational motions of both their inorganic and organic sublattices. Here, we demonstrate the ultrafast VC of FAPbBr3 perovskite solar cells via intramolecular vibrations of the formamidinium cation using spectroscopic techniques based on vibrationally promoted electronic resonance. The observed short (~300 fs) time window of VC highlights the fast dynamics of coupling between the cation and inorganic sublattice. First-principles modelling reveals that this coupling is mediated by hydrogen bonds that modulate both lead halide lattice and electronic states. Cation dynamics modulating this coupling may suppress non-radiative recombination in perovskites, leading to photovoltaics with reduced voltage losses.