Halide perovskites have been widely explored as efficient photo-responsive materials for applications in many optoelectronics areas owing to their unique optoelectronic properties and facile processing. However, the poor stability of these materials is still a substantial challenge for their commercialization.

Low-dimensional (two- or quasi-two-) perovskites, which are formed by introducing larger organic amine group into the perovskite structure, not only offer great potential for the development of high stability devices, but also achieve higher field-effect mobility due to the low ion migrations at room temperature. Despite of these promising merits of low-dimensional perovskite, their carrier transport properties are still lacking in-depth understanding. In this regard, developing an effective and facile strategy to monitor the internal carrier transport properties remains as a major challenge.

YU Weili’s research group from Changchun Institute of Optics, Fine Mechanics and Physics (CIOMP) of the Chinese Academy of Sciences (CAS) published relevant research findings on Small. They had in-depth insights on revealing the fundamental photo-physical processes and carrier transport features of two-dimensional (2D) perovskite materials through non-invasive and non-destructive surface-enhanced Raman scattering (SERS)-based approach and proposed a layered-carrier-transport model.

The organic material 3,4,9,10-Perylenetetracarboxylic Dianhydride (PTCDA) as a probe molecule not only broadened the instrinsic photo-responsive range of (PEA)₂PbBr₄, but also the vibrational mode changes of its Raman spectrum can clearly monitor the interfacial and internal charge transfer process, which related to the crystal structure within 2D perovskite.

Furthermore, the distinct difference of the voltage-dependent intrinsic Raman spectra of the bulk perovskite single crystal with different crystal orientations reflected the influence by the quantum confinement effect on the carrier anisotropic transport properties. At the same time, to elucidate the underlying carrier transport mechanism behind the Raman spectra, relevant theoretical simulation was carried out to explore the process.

In this study, we not only provided a promising way for elucidating the carrier transport properties within 2D perovskites at the molecular level, but also paved a way for optoelectronic devices designs and optimizations.