Infrared light (IR) detection principles limited by poor photoresponsivity and sparse photogenerated carrier make them impossible to directly applied in flexible IR sensing field attributed to low π-π conjugation effect, thick P-N junction, and harsh band gap, of which IR self-powered electronic skin (e-skin) strongly relies on the essential property of exotic photosensitive-exciting materials, hardly any flexible organic polymer or nanocomposites. Here, an innovative IR self-powered principle is reported that outstanding piezoelectric effect of poly(vinylidene fluoride) nanofibers (PVDF NFs) is driven by microcrystals' volume expansion caused by the solid-solid phase transition of PVDF/multiwalled carbon nanotubes (MWCNTs)/highly elastic phase change polymer (HEPCP) (PMH) nanocomposites due to MWCNT's excellent IR photoabsorption and thermal conversion capabilities. A flexible IR-sensitive nanocomposite is successfully developed employing PVDF/HEPCP NFs as the framework of a three-dimensional network structure wrapped by the MWCNT/HEPCP nanocomposite. The 33, 50, and 60 wt % PMH nanocomposites are demonstrated cyclic, IR-regulated on/off piezoelectric sensitivity of 889.7, 977.6, and 493.8 mV/(mW·mm-2) at IR powers of 5.3 mW/mm2, respectively. Furthermore, IR self-powered e-skin has been developed successfully and realized an accurate IR stimulus-sensing location due to the sensitivity, which depends on the size of the sensing area. This innovative strategy provides a new route to the fundamental science and applications of flexible IR self-powered devices, such as e-skin, artificial vision, soft robots, active surveillance sensors, etc.
Keywords: PVDF nanofibers; flexible electronic skin; infrared self-powered; piezoelectric effect; solid−solid phase transition.