Reversibly Light-Modulated Dirac Point of Graphene Functionalized with Spiropyran

Abstract

Graphene has been functionalized with spiropyran (SP), a well-known photochromic molecule. It has been realized with pyrene-modified SP, which has been adsorbed on graphene by π-π interaction between pyrene and graphene. The field-effect transistor (FET) with SP-functionalized graphene exhibited n-doping effect and interesting optoelectronic behaviors. The Dirac point of graphene in the FET could be controlled by light modulation because spiropyran can be reversibly switched between two different conformations, a neutral form (colorless SP) and a charge-separated form (purple colored merocyanine, MC), on UV and visible light irradiation. The MC form is produced during UV light irradiation, inducing the shift of the Dirac point of graphene toward negative gate voltage. The reverse process back to the neutral SP form occurred under visible light irradiation or in darkness, inducing a shift of the Dirac point toward positive gate voltage. The change of the Dirac point by UV and visible light was reproducibly repeated. SP molecules also improved the conductance change in the FET device. Furthermore, dynamics on conversion from MC to SP on graphene was different from that in solution and solid samples with SP-grafted polymer or that on gold nanoparticles.

Giant Dirac point shift of graphene phototransistors by doped silicon substrate current

“…There have been some reports of significant Dirac point shifts using graphene functionalized with spiropryan, 23 quantum dots coated on graphene, 24 and the tunneling structure of a thin insulator layer sandwiched by graphene. 25 However, these studies used additional components or new structures on conventional graphene-based phototransistors and produced a Dirac point shift.…”

Preparation and characterization of dual-responsive spiropyran-based random copolymer brushes via surface-initiated atom transfer radical polymerization

“…[34][35][36][37][38] The combination of spiropyran units (SP) into polymer and then attaching them onto SNPs can sharply reduce the fatigue of light-responsive polymer brushes. [39] As smart dynamic materials, the spiropyran-based copolymers have particular advantages for profound and lasting applications.…”

Triazatriangulene platform for self-assembled monolayers of free-standing diarylethene

“…Among various stimuli (e.g., redox process [10], pH [11], magnetic field [12]), light offers a clean, non-invasive, low-cost and easily addressable way for triggering molecular switches in electrical devices [13,14]. Diarylethene (DAE) is considered as one of the most promising group of photo-responsive molecules due to outstanding fatigue-resistance [15,16], compared with other photoswitches such as azobenzene [17] and spiropyrane [18]. Upon exposure to alternating UV and visible light, DAE isomerizes reversibly between the ring-open and closed states with distinguishing electronic properties as a result of the change in conjugated structure [19][20][21].…”