Jie Lin, Ling‐ling Xu, Yong Liu, Hang Gao, Huifeng Chen, Jing-Juan Xu
ABSTRACT Electrochemiluminescence (ECL) holds significant promise in the biomedical field, but remains a challenge for in vivo photodynamic therapy (PDT). Herein, a wearable light source of ECL to drive PDT (ECL‐PDT) is developed, in which a flexible ECL device (ECLD) is fabricated using an ECL gel containing Ru(bpy) 3 Cl 2 as the light‐emitting layer positioned between two transparent indium tin oxide‐coated substrates. By applying alternating current voltage, Ru(bpy) 3 + and Ru(bpy) 3 3+ are alternately generated within the ECLDs, and then collide to produce excited species, followed by high‐efficiency and stable ECL emission. The ECLDs can further activate photosensitizers to produce reactive oxygen species through a resonance energy transfer process, ultimately leading to oxidative damage of cancer cells. As a result, such ECLDs demonstrate excellent antitumor efficacy on cells, and tumor growth is distinctly inhibited in a tumor‐bearing mouse model. This work not only provides a convenient and effective ECL‐PDT strategy for cancer treatment, but also expands the application of ECLD as a wearable photonic healthcare device.