23 December 2021

[Perovskite] – Scientists reveal ultrafast exciton dissociation mechanism in 2D perovskites.

Home > News > [Perovskite] – Scientists reveal ultrafast exciton dissociation mechanism in 2D perovskites.
Flèche contenu
Perovskite - codex international

A research group led by Prof. JIN Shengye from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences revealed an ultrafast and high-yield polaronic exciton dissociation mechanism in two-dimensional (2D) perovskites.

This study was published in Journal of the American Chemical Society

2D perovskites are a class of naturally formed quantum well (QW) materials. The exciton binding energy in 2D perovskite is much larger (up to hundreds of meV) than that in their 3D counterparts due to strong quantum and dielectric confinement.

Therefore, it is commonly believed that the photogenerated charge carriers in 2D perovskites are mainly exist in the form of excitons, which are difficult to dissociate into free carriers at room temperature.

In this study, by using femtosecond photoluminescence up-conversion (PL-UC) and transient absorption (TA) spectroscopy, the researchers for the first time directly and dynamically observed the ultrafast (< 1.4 ps) and highly efficient (> 80%) exciton dissociation in 2D perovskites (n ≥ 2). This confirmed that free-carriers were the dominant carrier species in 2D perovskites under room temperature, which is conflict with previous thought.

Moreover, they proposed a polaron-induced exciton dissociation mechanism, where the exciton-polarons were readily formed by strong exciton-phonon coupling as in 3D perovskites, and the polaronic screening effect led to a prominent reduction in binding energy for efficient exciton dissociation.

The researchers demonstrated that the exciton dissociation into free-carriers was a major factor limiting the photoluminescence quantum yield of 2D perovskites by introducing additional nonradiative carrier loss.

“This work reveals a common exciton dissociation property in this class of 2D materials and provides a guideline for the design and rational utilization of 2D perovskites in optical and optoelectronic applications,” said Prof. JIN.


Discover Also
[Materials] – A nanoscale lattice of palladium and yttrium makes for a superlative carbon-linking catalyst 23 February 2020

A group of materials scientists at Tokyo Institute of Technology has shown that a palladium-based intermetallic electride, Y3Pd2, can improve the efficiency of carbon-carbon cross-coupling reactions. Their findings point the way to a more sustainable world through catalysis.

Read more
[Nanoparticles] – Self-Cleaning Clothing- What Role do Nanoparticles Play? 23 February 2020

The use of nanoparticles to enhance clothing is not a new development. Starting in the mid-2000s, many garment manufacturers began integrating silver nanoparticles with antimicrobial qualities into their products. More recently, major advancements have been made in self-cleaning fabrics that make use of nanoparticles.

Read more