TPP-Ce6 is a mitochondria-targeting photosensitizer formed by the ester linkage of chlorin e6 (Ce6) with triphenylphosphine (TPP). Upon light exposure, TPP-Ce6 generates reactive oxygen species (ROS), particularly singlet oxygen, which induce oxidative stress, leading to mitochondrial dysfunction and apoptosis (cellular apoptosis). This compound is useful for research on mitochondrial roles in apoptosis, energy metabolism, and cancer treatment.