Layered heterostructure enable sensitive thermosensation and high fire safety of flexible organic thermoelectric nanocoating

•A flexible thermoelectric nanocoating with layered heterostructure was constructed.•The nanocoating exhibited accurate detection capability for the temperature rise stage of a fire.•The nanocoating triggered fire-warning within 1.5 s when encountering fire.•The coated polymer materials were difficult to be ignited during burning tests.