Photomechaelectric Effect Based Flexible Polymer Nanogenerator

Benefiting from free electrons in metal and redistribution of holes and electrons for semiconductors under illumination, metal and inorganic or organic conjugate semiconductors can convert solar energy into electricity through the well-known external photoelectric effect and internal photovoltaic effect, respectively. Photoelectric effect cannot be detected in typical electron-insulated polymers due to they are lack of free electrons or redistribution of holes and electrons under illumination. Herein, we for the first time report a subtle method to convert light energy into electricity for electron-insulated polymers via a novel photomechaelectric (PME) effect, in which PME effect means that photo induces isomerization of photo-sensitive units in macromolecular chains and further results in generating dynamic dipoles and equal amount but opposite signs of induced charges at electrodes. To this aim, functional azobenzene (AZO) and imidazole ionic liquid (ILO) oligomers have been synthesized and used as photoisomer and dipole units, respectively. Transparent AZO-co-ILO copolymer based nanogenerators (PME-NGs) have been assembled and related power generation performance and mechanism are investigated. The produced electron-insulated PME-NGs can directly output an alternating current (up to 5.8 V and 247 µA) under UV illumination, implying large potential application in the fields of flexible and wearable self-powered electronic devices.