Fernando Martín (UAM) — Optical properties of acceptor-molecule-donor complexes adsorbed on Graphene/SiC(0001)

💡 A new RES Success Story about optoelectronics and graphene💡 

📋 "Optical properties of acceptor-molecule-donor complexes adsorbed on Graphene/SiC(0001)" led by Fernando Martín from Universidad Autónoma de Madrid

Silicon carbide (SiC) is becoming important as a semiconducting base for growing graphene since graphene-like buffer layer forms at the interface with SiC, showing distinct electronic properties, which allows for molecule adsorption. The charge-carrier concentration can be adjusted by adsorbing certain molecules, such as strong electron acceptors for p-type doping.

🔦 Previous research mainly focused on experimental methods to study graphene-SiC, particularly its ground-state properties, but this study explored both electronic and optical characteristics of the interface. The team used many-body perturbation theory (MBPT) to yield deeper understanding of electronic interactions and excitations than typical simulations and aligning well with experiments. 

🖥 Thanks to RES supercomputer hashtag#PirineusIII from Consorci de Serveis Universitaris de Catalunya (CSUC), they found that when graphene is adsorbed onto SiC, the quasiparticle band structure exhibits a reduced bandgap, which is linked to optical activities in the visible spectrum. 

The adsorption of electron-accepting molecules further alters this bandgap, creating unique low-lying optically excited states in the near-infrared range that are important for molecular optoelectronics due to their wavelength selectivity.

🖼 In the image, there is the absorption spectra for the substrate without and with the electron-accepting molecules: TCNQ (left) and F4TCNQ (right)adsorbate. Vertical green bars represent transitions with oscillator strength >0.1.