Self-Adhesive Nanofilms Overcome Interface Challenges in Solar–Thermal–Electric Conversion for High Power Output and 90-Cycle Stability

Materials for reusable, stable, and efficient solar–thermal–electric (STE) conversion are crucial for sustainable energy. However, most photothermal materials face challenges due to inhomogeneous interfaces when integrated with thermoelectric (TE) modules, compromising stability and efficiency. Herein, we synthesize self-adhesive nanofilms (55–60 nm thick, roughness <3 nm) at the humid air/dimethyl sulfoxide interface using tailored building blocks. The nanofilms exhibit broad absorption (250–1500 nm) and a rapid solar–thermal response, reaching a temperature increase of >100 °C under 3 suns within 200 s. The imine groups and nanoscale thickness endow the film with strong adhesion to diverse substrates, including filter paper, poly(dimethylsiloxane), fabrics, silicon, and TE modules. The nanofilm maintains robust adhesion under extreme pH variations, water rinsing, forced convection, thermal shocks, and organic solvent immersion. When integrated with a TE module, the resulting STE device achieves a high actual power output of 1.46 W m–2 (open-circuit voltage, 397 mV; short-circuit current, 32.9 mA) under 1 sun irradiation. Remarkably, the device shows no performance degradation after 90 cycles, demonstrating exceptional stability. Practical applicability is highlighted by continuous electrical output from a four-device array floating on a lake. This study opens an avenue in interfacial engineering for ultrastable STE devices, accelerating superior energy harvesting.