Fluence-Dependent Morphological Transitions in Laser-Induced Graphene Electrodes on Polyimide Substrates for Flexible Devices

Abstract

Laser carbonization of polymers is an emerging technique that enables directly patterning conductive carbon electrodes for a plethora of flexible devices, including supercapacitors and sensors. While these laser-induced nanocarbon (LINC) patterns were previously shown to have various hierarchical porous and fibrous graphene-based morphologies, the fundamental mechanisms underlying the formation of specific LINC morphologies is still largely missing. Here, we present a method for lasing polyimide films with spatially controlled gradients of optical energy flux. Combined with Gaussian beam modeling, our approach uniquely enables continuously sweeping different laser fluence values as a spatial map along the laser path. We find that above the fluence value of 5 J/cm2, progressive carbonization and swelling results in porous LINC. We also identify two additional thresholds that correspond to morphological transitions: first, from isotropic porous morphology to anisotropic networks at 12 J/cm2; second, from anisotropic networks to aligned nanofibers at 17 J/cm2. Our results show that anisotropic cellular networks are the most electrically conducting and have the highest quality sp2 carbon. However, the aligned woolly nanofiber morphology is electrically insulating along the length of the lased lines, although they exhibit the highest degree of carbonization with the least heteroatom content. Hence, our results provide insights into the fluence-dependence of the physicochemical processes underlying LINC formation. Moreover, our approach enables generating a morphology diagram for LINC, which facilitates precise tunability of both the morphology and properties of LINC patterns, based on easy-to-control processing parameters, such as laser power and degree of beam defocusing.

Laser-Induced Graphene Based Flexible Electronic Devices

“…Meanwhile, the conductivity, electrochemical performance [24,27,35,36], biocompatibility [37,38], and hydrophobicity [39][40][41] of LIG also have been systematically studied. A variety of LIG devices have been developed, including sensors [14][15][16][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42], supercapacitors [17,[43][44][45][46][47][48][49][50][51][52][53][54][55], nanogenerators [54][55][56][57][58]…”

“…Furthermore, a variety of natural and synthetic materials, ranging from plants [ 22 , 23 , 24 ], textiles [ 24 , 25 , 26 , 27 ], papers [ 28 , 29 , 30 ] to other organic films [ 17 , 27 , 31 , 32 , 33 , 34 ], are experimentally demonstrated in serving as the carbon source to form LIG. Meanwhile, the conductivity, electrochemical performance [ 24 , 27 , 35 , 36 ], biocompatibility [ 37 , 38 ], and hydrophobicity [ 39 , 40 , 41 ] of LIG also have been systematically studied. A variety of LIG devices have been developed, including sensors [ 14 , 15 , 16 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 ], supercapacitors [ 17 , 43 , 44 , …”

“…Meanwhile, the conductivity, electrochemical performance [ 24 , 27 , 35 , 36 ], biocompatibility [ 37 , 38 ], and hydrophobicity [ 39 , 40 , 41 ] of LIG also have been systematically studied. A variety of LIG devices have been developed, including sensors [ 14 , 15 , 16 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 ], supercapacitors [ 17 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 ], nanogenerators [ 54 , 55 , 56 , 57 , 58 , 59 , 60 , …”

Status and Prospects of Laser‐Induced Graphene for Battery Applications

“…Furthermore, Abdulhafez et al used spatially controlled gradients of optical energy flux and Gaussian beam modeling to generate a precise morphology diagram for LIG based on laser power and degree of beam defocusing. [37] The merits of LIG endow it with various energy-environmental-related applications, such as sensors, [38][39][40][41] supercapacitors, [42][43][44][45][46] and water treatment. [47] These properties triggered researchers to explore other precursors than GO and PI films.…”

Enhancement of antibacterial function by incorporation of silver-doped ZnO nanocrystals onto a laser-induced graphene surface

“…9 By controlling laser parameters and atmospheric conditions, morphology and hydrophobicity of the LIG can be altered. 16,17 Owing to exceptional physical and chemical properties, the LIG has broad applications in mechanic sensors, 15,18,19 chemical sensors [20][21][22] and supercapacitors. [23][24][25] Subsequently, many polymers and natural materials have been converted to the LIG, including polydimethylsiloxane (PDMS), 18 bread, wood, etc.26 In recent years, antimicrobial nanocarbons has rapidly attracted the attention of many researchers because of its excellent antibacterial properties.…”