PSs with AIE feature . By adjusting the ClogP value (3~5), these positively charged AIEgens could selectively stain G+ bacteria without any extra targeting groups. Benefiting from the excellent specificity to G+ bacteria, effective ROS generation ability, and bright NIR emission, these AIEgens were successfully utilized for the selective photodynamic theranostics of S. aureus. This successful example on structure-activity relationship study could provide guidance for the further exploration of novel antibacterial theranostic agents.