Photoluminescent Semiconducting Graphene Nanoribbons via Longitudinally Unzipping Single-Walled Carbon Nanotubes

Abstract

The lack of a sizeable band gap has so far prevented graphene from building effective electronic and optoelectronic devices despite its numerous exceptional properties. Intensive theoretical research reveals that a band gap larger than 1 eV can only be achieved in sub-3 nm wide graphene nanoribbons (GNRs), but real fabrication of such ultranarrow GNRs still remains a critical challenge. Herein, we demonstrate an approach for the synthesis of ultranarrow and photoluminescent semiconducting GNRs by longitudinally unzipping single-walled carbon nanotubes. Atomic force microscopy reveals the unzipping process, and the resulting 2.2 nm wide GNRs are found to emit strong and sharp photoluminescence at ∼685 nm, demonstrating a very desirable semiconducting nature. This band gap of 1.8 eV is further confirmed by follow-up photoconductivity measurements, where a considerable photocurrent is generated, as the excitation wavelength becomes shorter than 700 nm. More importantly, our fabricated GNR field-effect transistors (FETs), by employing the hexagonal boron nitride-encapsulated heterostructure to achieve edge-bonded contacts, demonstrate a high current on/off ratio beyond 105 and carrier mobility of 840 cm2/V s, approaching the theoretical scattering limit in semiconducting GNRs at room temperature. Especially, highly aligned GNR bundles with lengths up to a millimeter are also achieved by prepatterning a template, and the fabricated GNR bundle FETs show a high on/off ratio reaching 105, well-defined saturation currents, and strong light-emitting properties. Therefore, GNRs produced by this method open a door for promising applications in graphene-based electronics and optoelectronics.

Flexible and Stretchable Carbon-Based Sensors and Actuators for Soft Robots

“…( h ) Figure for mechanical exfoliation: Reproduced from [ 84 ] with permission, copyright 2019, Elsevier. ( i ) Figure for unzipping of carbon nanotubes: Reproduced from [ 86 ] with permission, copyright 2021, ACS.…”

Graphene-Oxide-Based Fluoro- and Chromo-Genic Materials and Their Applications

“…Graphene is an outstanding representative of the 2D materials family and it is also the most studied 2D material, exhibiting a range of remarkable properties such as outstanding mechanical strength, excellent electrical conductivity, high thermal conductivity, good light transmittance, ultrahigh carrier mobility, large surface area and flexibility [ 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ]. Furthermore, graphene shows complete impermeability to gases.…”

Enhanced Ammonia Gas Adsorption through Site-Selective Fluorination of Graphene

“…Graphene has been extensively explored as an ideal material in solid state gas sensors due to its atomically thin two-dimensional structure, large specific area and superior electrical properties [1][2][3][4][5][6]. The past decade has witnessed the advancement of graphene sensors and a number of graphene-based gas sensors have been applied for sensing various gases, such as NO 2 [7,8], NO [9] and CO 2 [10] among others.…”