Year: 2025
Type: article
Abstract: NbOI 2 has recently emerged as a new van der Waals material combining semiconducting behavior with intrinsic in-plane ferroelectricity and pronounced transport and optical anisotropy. However, its photocarrier dynamics remain largely unexplored. Here, we report transient absorption spectroscopy of NbOI 2 using femtosecond pump–probe measurements. A pronounced transient absorption feature is observed near the 2.34 eV excitonic resonance, arising from photocarrier-induced excitonic energy shifts and saturation. The decay dynamics reveal an exciton lifetime of several tens of picoseconds. The observed density-dependent behavior is consistent with exciton–exciton annihilation and defect-assisted Auger recombination, yielding a rate of 0.4 cm 2 s –1 . Polarization-resolved measurements further reveal a pronounced in-plane anisotropy in the transient response that follows the linear absorption anisotropy. These findings provide fundamental insight into photocarrier dynamics in NbOI 2 and establish key parameters for understanding and exploiting its optoelectronic behavior.
Source: Nano Letters
Authors: Salman Ahsanullah, Neema Rafizadeh, Hui Zhao
Institution: University of Kansas
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W4417535436