Tailoring Long-Lived Charge Separation Enables Efficient Light-to-Heat Conversion for Efficient Cancer Therapy

Treating cancer with organic materials that absorb light and release heat offers the possibility of more targeted therapy with reduced side effects. However, the low photothermal conversion efficiency (PCE) in many organic materials means that high laser powers are needed, raising safety concerns and limiting clinical adoption. Here, we present a molecular design strategy that achieves excellent efficiency in converting light to heat for cancer treatment. By engineering molecules in which key chemical groups are locked at right angles, we created structures that can hold separated electrical charges for extended periods while efficiently converting this energy into heat. An embodiment of this material that we term MNTPAA achieved a PCE of 91.47% under near-infrared (NIR) light irradiation. In a mouse model of aggressive breast tumors, MNTPAA/NIR treatment not only eliminated the cancer but also stimulated the immune system against recurrence. This molecular engineering strategy provides an effective approach to constructing highly efficient light-activated materials. It facilitates the rational design of additional systems featuring long-lived charge separation states, supporting the development of versatile photothermal agents with enhanced therapeutic efficacy.