Variable Range Hopping in Self-Encapsulated Carbon Features by Internal Resin Direct Laser Writing Carbonization Method

The internal resin direct laser writing carbonization(IR-DLWc) method is a simple but powerful technique that enables in-situ direct writing of self-encapsulated carbon structures within the interior of polyimide film via CO 2 infrared laser. Combined optical characterization and temperature-dependent electrical measurements were performed to study the charge transport behavior of IR-DLWc samples. The three-dimensional variable range hopping (3D-VRH) conduction model was found appropriately to explain for the temperature-dependent sheet resistance results for all the IR-DLWc samples prepared in this study, as well as the two conventional DLWc samples used for comparative research. All the IR-DLWc samples tested in this study shew much higher T0 values than conventional DLWc samples, implying highly localized electronic states. For the first time, the conductivity decay of IR-DLWc and conventional DLWc samples being continuously monitored over a 4-year period, showing that the conductivity of DLWc samples exposed to air decayed rapidly at first and then significantly slowed down. In contrast, the IR-DLWc samples and UV-glue-encapsulated DLWc samples very unexpectedly exhibited a slightly slower initial conductivity decay rate, yet continued to decay over time, faster ultimately than the DLWc samples exposed to air, which shew the complexity of the interaction between air and laser-induced carbon materials.