Differentiating the origins of local charge transfer in oxides and hybrid halides by accumulating charge†

Abstract

Unveiling the origin of local charge transfer is crucial for advancing electronic devices such as ferroelectric and memristive memories and perovskite solar cells. Exploring charge transfer mechanisms requires sensitive probing of local charge transfer, as electric charges in many materials arise from multiple mechanisms. However, the limited sensitivity of current techniques makes it challenging to unveil the origins of such nanoscale charge behavior. To address this challenge, we propose highly sensitive accumulative charge transfer spectroscopy (ACTS) for probing dynamic charge behaviors at the nanoscale in oxides and hybrid halides, including Pb(Zr_0.2Ti_0.8)O₃, Hf_0.5Zr_0.5O₂, TiO₂ and FAPbI₃. In ferroelectrics, clear polarization switching charges were detected through accumulative charges generated from a series of relatively low-voltage waveforms, achieving a high sensitivity of 6.66 MV m⁻¹. In contrast, distinctive charge behaviors, potentially associated with oxygen vacancy migration and trap states, respectively, were identified in memristive and hybrid halides. This work demonstrates the potential of ACTS for direct, localized discrimination of charge transfer behaviors at the nanoscale.