Electronic Disorder Dominates the Charge-Carrier Dynamics in Two- Dimensional/Three-Dimensional Organic-Inorganic Perovskite Heterostructure

Constructing two-dimensional (2D)/three-dimensional (3D) organic-inorganic hybrid perovskite (OIHP) heterostructures is a promising strategy to simultaneously reduce defects and improve the stability of perovskite solar cells (PSCs). However, its regulating mechanism is not fully understood. In this study, we apply femtosecond time-resolved optical-pump terahertzprobe spectroscopy, supplemented by UV-vis absorption spectra measurements, to investigate charge-carrier dynamics of 2D/3D OIHP heterostructures and establish a correlation among effective charge-carrier mobility, hot-carrier cooling time, phonon frequency, and electronic disorder. We demonstrate that the electronic disorder dominates the charge-carrier dynamics during the heterojunction engineering in 2D/3D OIHPs and causes an exponential decrease in effective charge-carrier mobility and hot-carrier cooling time. The electronic disorder, quantitatively characterized by the Urbach energy, can offer an effective and general descriptor for evaluating the properties of 2D/3D hybrid perovskite materials. This work provides useful guidelines for boosting the performance of PSCs and optoelectronic devices by minimizing the Urbach energy.