Jian-Duo Lu

A Review on Organic Polymer-Based Thermoelectric Materials

Converting heat energy directly into useable electricity by harvesting low-cost energy resources, such as solar energy and the waste heat, has attracted great interest recent years. Thermoelectricity offers a promising technology to convert heat from solar energy and to recover waste heat from industrial sectors and automobile exhausts. Classically, a number of inorganic compounds have been considered as the best thermoelectric materials. Organic materials in particular intrinsically conducting polymers had been considered as competitors of classical thermoelectric since their figure of merit has been improved several orders of magnitude in last year. In addition, the applications of thermoelectric polymers at low temperatures have shown various advantages such as easy and low cost of fabrication, light weight, and flexibility. Therefore, organic thermoelectric materials will be the best candidates to compete with inorganic materials in the future. In this review, we focused on exploring different types of organic thermoelectric materials and the factors affecting their thermoelectric properties, and discussed various strategies to improve the performance of thermoelectric materials. In addition, a review on theoretical studies of thermoelectric transport in polymers is also given.

The conductance and magnetoresistance effect in a periodically magnetically modulated nanostructure

In this paper, we theoretically investigate the conductance and the magnetoresistance effect in a periodically magnetically modulated two-dimensional electron gas. It is shown that there exists a significant conductance difference for electrons through the parallel and antiparallel magnetization configurations, which leads to a considerable magnetoresistance effect. It is also shown that the conductance and the magnetoresistance effect depend on both the temperature and the number of the periodic magnetic barriers.

The effects of the barrier and δ-doping on the electron tunneling in a nonmagnetic heterostructure

In this paper, we investigated the spin-dependent electron transport in a nonmagnetic nanostructure under the influence of the δ-doping which can be experimentally doped in the nanostructure with metal-organic chemical vapor deposition or molecular beam epitaxy. The numerical results indicate that the large spin polarization nearly 100% can be achieved in such a structure without the external magnetic field due to spin–orbit interactions and it can be controlled not only by the barrier, but also by the δ-doping. These interesting finds are very valuable for designing the δ-doping-tunable spintronic device based on the nonmagnetic nanostructure.

QUANTUM ELECTRON CONDUCTANCE OF FOUR-TERMINAL JUNCTIONS

With the help of the scattering-matrix method, the quantum states of ballistic electrons and conductance, as well as resistance are studied in a four-terminal junction of narrow wire with various widths. We find that these observable quantities are highly sensitive to the geometries of junctions and differ from the conventional structure with the same width. In particular, the predicted quantization conductance phenomena are striking and are also in self-consistency with calculated scattering probabilities, relating to electronic subbands and transmission states.