Dramatic Enhancement of Optoelectronic Properties of Electrophoretically Deposited C₆₀–Graphene Hybrids

Abstract

Fullerene (C60) and multilayer graphene hybrid devices were fabricated using electrophoretic deposition, where the C60 clusters are electrically charged upon the application of an external bias in a polar solvent, acetonitrile, mixed with toluene, which facilitates their deposition on the graphene membranes. Raman spectroscopy unveiled the unique vibrational fingerprints associated with the A2g mode of the C60 molecules at ∼1453 cm–1, while blue shifts of ∼6 and ∼17 cm–1 were also attributed to the G- and 2D-bands of the hybrids relative to bare graphene, suggestive of p-doped graphene. The intensity ratio of the G- and the 2D-bands I 2D/I G (hybrid) dropped to ∼0.18 from ∼0.3 (bare graphene), and this reduction in I 2D/I G is also a signature of hole-doped graphene, consistent with the relatively strong electron accepting nature of C60. The electronic conductance of the two-terminal hybrid devices increased relative to bare graphene at room temperature which was attributed to the increased carrier density, and temperature-dependent electronic transport measurements were also conducted from ambient down to ∼5.8 K. Additionally, a low energy shift in the Fermi level, E F ≈ 140 meV, was calculated for the hybrids. When the hybrid devices were irradiated with a broadband white light source and a tunable laser source (with a wavelength λ ranging from ∼400–1100 nm), a strong photoresponse was evident, in contrast to the bare graphene devices which appeared unresponsive. The responsivity of the hybrids was measured to be ∼109 A/W at λ ≈ 400 nm and ∼298 K, while the detectivity and external quantum efficiency were also exceptional, ∼1015 jones and ∼109%, respectively, at ∼1 V and a light power density of ∼3 mW/cm2. The values are ∼10 times higher compared to other hybrid devices derived from graphene reported previously, such as quantum dot-graphene and few-layer MoS2–graphene heterostructures. The strong photoresponse of the C60–graphene hybrids reported here is attributed to the doping enhancement arising in graphene upon the adsorption of C60. This work demonstrates the exceptional potential of such hybrid nanocarbon-based structures for optoelectronics.

Phosphorene–Fullerene Nanostructures: A First-Principles Study

“…Consequently, carbon fullerenes act as mild p-dopants for phosphorene, introducing up to 0.3 holes/molecule on the substrate. Moreover, carbon, boron, boron nitride, and silicon carbide fullerenes have also behaved as p-dopants upon adsorption on related 2D materials such as pristine graphene and metal-doped graphene 40,42,[49][50] .…”

“…Since the bandgap value is directly proportional to the conductance (  HL/kT, where k is the Boltzmann constant and T the temperature), our results define a framework to explore the charge-transport and optoelectronic response of Phos-Fullerene nanostructures. As an illustration, the increased charge transport of graphene due to C60 deposition [54][55] , and the strong electron-accepting characteristics of C60 causing a hole-doped nature in graphene, lead to hybrid structures allowing photogenerated carriers for high-performance photodetector devices 50 . It is also noticed that a larger electron transfer in the Phos→Fullerene direction is responsible for lower bandgap values, resulting in a higher conductance.…”

Photocurrent Generation Mechanisms in Molybdenum‐Contacted Semiconducting Black Phosphorus and Contributions from the Photobolometric Effect

“…The vast body of research on graphene since 2004 has led to the exploration of a broader family of 2D‐layered materials, [ 1,2 ] with properties including insulators (e.g., h‐BN), semiconductors (e.g., WSe 2 and SnSe 2 ), metals (e.g., TiS 2 ) to superconductors (e.g., NbSe 2 ). The rich variety of properties emergent in these systems, including the transition metal di‐chalcogenides (TMDCs), have given way to excitonic behavior observed even in solution‐dispersions, [ 3 ] flexible van der Waals electronics, [ 4 ] composites, [ 5 ] fullerene–2D hybrids, [ 6 ] quantum multibody systems, [ 7 ] and biocompatible optoelectronics. [ 8 ] More recently, semiconducting black phosphorous (BP), the most stable phosphorous allotrope when compared with its other forms, such as red, purple, or white phosphorus, has been rediscovered in its 2D structural motif.…”

Facilitated Interfacial Electronic Processes by the π–π Stacked Edge-on Tetrabenzoporphyrin/Graphene Layer Enables Broadband Ultrasensitive Photodetecting with Prompt Response

“…Photodetectors are one of the key functional units in modern technologies and used widely in assorts of areas, such as medical and biological imaging, flame detection, optical communication, astronomical exploration, and wearable health-monitoring devices in future. − To boost the photosensing performances, the optical and electronic properties of photodetecting materials need to be balanced deliberately. Graphene (Gr) materials demonstrate promising applications in the photosensing areas because of their wide spectrum-absorbing range, high charge carrier mobilities, and excellent mechanical and flexible properties. , However, low responsivity ( R ) of pristine graphene resulted from the poor efficiency of light absorption and short lifetime of photogenerated charge carriers need to be improved to meet the demands of the applications. , Assorts of strong light-absorbing materials were combined with graphene to enhance the photodetecting properties, including inorganic/graphene oxide nanostructures, ,− other two-dimensional materials, − and organic components. ,− Creating defects on Gr sheets can amend the abilities of light absorption as well, − but will sacrifice charge carrier mobilities more or less. Organic/Gr hybrids are especially attractive because of a massive number of available organic species, low cost and scalable solution fabricating approaches, and excellent flexibility desired highly for foldable/wearable devices. , …”