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Li, Guangqi

Publications and source records attributed to Li, Guangqi.

4 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Optically induced transport through semiconductor-based molecular electronics

A tight binding model is used to investigate photoinduced tunneling current through a molecular bridge coupled to two semiconductor electrodes. A quantum master equation is developed within a non-Markovian theory based on second-order perturbation theory with respect to the molecule-semiconductor electrode coupling. The spectral functions are generated using a one dimensional alternating bond model, and the coupling between the molecule and the electrodes is expressed through a corresponding correlation function. Since the molecular bridge orbitals are inside the bandgap between the conduction and valence bands, charge carrier tunneling is inhibited in the dark. Subject to the dipole interaction with the laser field, virtual molecular states are generated via the absorption and emission of photons, and new tunneling channels open. Interesting phenomena arising from memory are noted. Such a phenomenon could serve as a switch.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

The influence of polaron formation on exciton dissociation

A linear tight-binding model was used to examine the yield of exciton dissociation under the influence of the electron–vibration interaction. The system consists of a linear chain, coupled to a single vibration, and electron–vibration interaction is permitted to occur on certain sites. In the presence of this interaction, population tends to localize to build a polaron. The system loses polaron trapping energy to the environment through its coupling to the bath environment, and loses population due to the injection into the electrode at the terminal site. A self-energy term was generated from population injection, and was added to the energy level of the last site, working as a sink function to absorb the electrons and measure the yield. This injection occurs only when the electron energy is inside and around the band. When the electron energy is outside the tight-binding band, population injection is inhibited. Our aim here is to investigate the exciton dissociation effected by the competition between polaron formation and population injection, via a process strongly influenced by the inter-site coupling and the electron–vibration interaction.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗