Flexible Organic Molecular\nSingle Crystal-Based Triboelectric\nDevice as a Self-Powered Tactile Sensor

Triboelectric nanogenerators (TENGs) have proven to be\neffective\nat converting mechanical energy into electrical power, making them\na viable technology for operating self-powered electronic devices\nused in medical diagnostics and environmental monitoring. In the present\nstudy, we demonstrate the utility of the flexible single crystals\nof an organic compound for the fabrication of a TENG as a self-powered\ntactile sensor. Triboelectrification was attained in single crystals\nas a result of surface functionalization with positively and negatively\ncharged moieties, viz. Zn<sup>2+</sup> and F<sup>–</sup>, respectively,\nwhich resulted in a variable surface potential and reversible adhesion\nthrough electrostatic interaction and induction phenomena. TENG incorporating\nthe single crystals showed an output voltage of 2.4 V, a current density\nof ∼2.2 μA/m<sup>2</sup>, and a power density of ∼850\nmW/m<sup>2</sup> and was capable of charging commercial capacitors\nthereby ensuring its ability to be used as a self-powered touch sensor.\nCapitalizing on these features, a self-powered tactile sensor was\nfabricated to demonstrate limb movements. The excellent mechano-electric\nsensitivity (∼102 mV/kPa until 6 kPa range) and response time\n(∼38 ms) establish the viability of flexible organic single\ncrystals for mechanical energy harvesting and biosensing applications\nthat could pave the way for their utilization as biomedical wearable\ndevices.