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Friday 03.07.2020
ITF zoom seminar10:00
Location Join zoom seminar: https://us02web.zoom.us/j/88260414282?pwd=Q0FBMjRnMytTUytGRDRVTUZ2TUJhQT09 pw: 916716 /
Speaker Pritam Bhattacharyya
Topic Pariser-Parr-Pople Model Based Electron Correlated Study of Linear Optical Absorption Spectra in Armchair-shaped Triangular Graphene Quantum Dots
Graphene quantum dot offers many potential applications due to their tunable band gaps and optical properties, depending on their shape and size. Recently, Yuan and coworkers claimed that the armchair-type triangular graphene quantum dots (TQDs) could be a promising candidate for optoelectronic applications, due to their good stability, high-performance, and high color-purity. This investigation set the stage to fabricate high-performance next-generation TQDs-based lightemitting diodes. In this work, the electronic and optical properties of various armchair-shaped TQDs were investigated. For the purpose, we carried out semi-empirical calculations by employing standard and screened parameters in the Pariser-Parr-Pople (PPP) model Hamiltonian, and the electron-correlation effects were incorporated using either QCI or MRSDCI approach, both for the ground and the excited states of the TQDs. On top of wave function based calculations using a higher level of theory, the accuracy of our results is further increased due to the long-range Coulomb interaction term present in the PPP model. Our computed results reveal that the optical spectra are blue-shifted with the decreasing size of the TQDs. In each optical absorption spectra, the first peak, which corresponds to the optical gap, is extremely-narrow as well as highly-intense and appeared due to transition at the band-edge, indicating that armchair-shaped TQDs are exceptionally unique for light-emitting diode (LED) fabrication. For the larger TQD considered in this work, we found good agreement with the experimental data. Finally, we discuss the influence of the symmetry in optical absorption based on the PPP model.


Invited by Dr. Liviu Hozoi
Contact Grit Rötzer

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