Capturing Ultrafast Carrier and Exciton Transport: Advances in Wide-Field Transient Absorption Microscopy

Understanding carrier and exciton transport with a high spatiotemporal resolution is essential for the advancement of next-generation electronic and optoelectronic devices. However, traditional time-resolved spectroscopic techniques are constrained in their ability to resolve spatially dependent ultrafast dynamics. In recent years, transient absorption microscopy (TAM) has emerged by integrating time-resolved spectroscopy with optical microscopy, enabling the simultaneous capture of spatial and temporal evolution of photoinduced carrier transport processes. Nevertheless, the point-scanning nature of conventional TAM leads to long acquisition times and imposes stringent requirements on laser stability and sample robustness, which significantly limit its application. Wide-field transient absorption microscopy (WTAM) effectively addresses these limitations by combining femtosecond temporal resolution with subdiffraction spatial imaging across a broad field of view, thereby enabling direct and rapid visualization of carrier and exciton diffusion and transport dynamics. In this review, we present the fundamental principles and instrumentation of WTAM, and summarize its unique advantages in mapping spatiotemporal dynamics. We further highlight recent advances in applying WTAM to investigate both equilibrium and nonequilibrium transport processes in various materials including perovskites, organic semiconductors, and two-dimensional materials. Finally, we discuss current challenges and propose future opportunities for expanding WTAM's role in characterizing advanced materials and guiding the design of high-performance optoelectronic devices.