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Báo cáo hóa học: "Efficient thermoelectric energy conversion on quasi-localized electron states in diameter modulated nanowires"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Efficient thermoelectric energy conversion on quasi-localized electron states in diameter modulated nanowires | Zianni Nanoscale Research Letters 2011 6 286 http www.nanoscalereslett.eom content 6 1 286 o Nanoscale Research Letters a SpringerOpen Journal NANO EXPRESS Open Access Efficient thermoelectric energy conversion on quasi-localized electron states in diameter modulated nanowires Xanthippi Zianni Abstract It is known that the thermoelectric efficiency of nanowires increases when their diameter decreases. Recently we proposed that increase of the thermoelectric efficiency could be achieved by modulating the diameter of the nanowires. We showed that the electron thermoelectric properties depend strongly on the geometry of the diameter modulation. Moreover it has been shown by another group that the phonon conductivity decreases in nanowires when they are modulated by dots. Here the thermoelectric efficiency of diameter modulated nanowires is estimated in the ballistic regime by taking into account the electron and phonon transmission properties. It is demonstrated that quasi-localized states can be formed that are prosperous for efficient thermoelectric energy conversion. Introduction A measure of the thermoelectric efficiency of a material is the dimensionless figure of merit ZT S2ơT k where Ơ is the conductivity s is the thermopower K is the thermal conductivity and T is the absolute temperature. In nanostructures quantum confinement of electrons and phonons favours their thermoelectric transport properties resulting in increased thermoelectric efficiency 1 . Nanowires and arrays of nanodots are currently attracting much research interest. It has been theoretically shown that nanodots can have very high thermoelectric efficiencies due to their discrete energy spectrum 2-4 . Quantum confinement causes enhancement of ZT in nanowires. Considerably high values of the figure of merit have been found in very thin wires 5-8 . Despite the noticeable progress in the fabrication of wires with high aspect ratios the poor mechanical properties of very thin wires is a drawback for