Polarity‐triggered anti‐Kasha system for high‐contrast cell imaging and classification

Abstract Kasha's rule, which states that all exciton emissions occur from the lowest excited state and are independent of excitation energy, makes high‐energy excitons difficult to use and severely hinders the widespread applications of organic photoluminescent materials in the real world. For decades, scientists have tried to break this rule to unleash the power of high‐energy excitons, but only minimal progress has been achieved, with no rational guiding principles provided, and few applications developed. So far, breaking Kasha's rule has remained a purely academic concept. In this paper, we introduce a design principle for a purely organic anti‐Kasha system and synthesise a series of compounds based on the design rule. As predicted, these compounds all display evident S 2 emissions in dilute solutions. In addition, we introduce a highly accurate (over 90%) convolutional neural network as an assistant for the classification of cells using anti‐Kasha luminogens, thereby providing a new application direction for anti‐Kasha systems.