Excitation Wavelength Dependent Reversible Photoluminescence Peak in Iodide Perovskites

TL;DR

This study reveals a reversible, excitation wavelength-dependent photoluminescence peak in iodide perovskites, linked to photoinduced structural changes, offering new opportunities for optoelectronic device functionalities.

Contribution

It demonstrates the existence of a reversible PL peak in iodide perovskites under femtosecond laser excitation, expanding understanding of their optical behavior.

Findings

Reversible PL peak depends on excitation wavelength and laser power.

Multiple peaks appear at different excitation energies.

Phenomenon observed across various iodide perovskite materials.

Abstract

Halide perovskites have indisputably exceptional optical and electronic properties, which are attractive for next-generation optoelectronic device technologies. We report on a reversible photoluminescence (PL) peak in iodide-based organic-inorganic lead halide perovskite materials under a two-photon absorption (TPA) process, while tuning the excitation wavelength. This phenomenon occurs when the incoming femtosecond (fs) laser photon energy is higher than a threshold energy. Intriguingly, this phenomenon also occurs in other kinds of iodide perovskite materials. Moreover, two more shorter wavelength peaks exhibit and become prominent when the excitation photon energy is being tuned in the high energy wavelength spectrum, while laser power is remained constant. However, the spectral PL energy window between the original material peak and the first high energy peak can vary based on the optoelectronic properties of the prepared films. The same phenomenon of reversible PL peak is also observed in various iodide based organic-inorganic halides as well as all-inorganic perovskite single crystals and polycrystals. We attribute to the reversible PL peak to the photoinduced structural deformation and the associated change in optical bandgap of iodide perovskites under the femtosecond laser excitation. Our findings will introduce a new degree of freedom in future research as well as adding new functionalities to optoelectronic applications in these emerging perovskite materials.