Microscopic time-resolved spectroscopy of organic crystals at the nanometer and micrometer scale

How can the photoexcitation dynamics processes of solid substances be measured at the microscopic level? This is a popular topic in many fields of basic and applied sciences. Organic crystals are one of many materials, and understanding their intrinsic properties at the microscopic level is the focus of this discussion. Microscopic time-resolved spectroscopy can study the morphology-dependent photoexcitation dynamics and energy spatial transport processes in organic crystals. In this tutorial review, we introduce the principles and methods of microscopic time-resolved photoluminescence and microscopic transient absorption techniques, which are currently or potentially used to study organic crystals at the nanometer and micrometer scale. Meanwhile, the research status of organic crystals investigated via microscopic time-resolved spectroscopy is discussed, with several examples provided. We then compare the advantages and disadvantages of different methods in detail, offering insights into potential improvements for instrument performance.