Thermoelectric Properties of Al-Doped Mesoporous ZnO Thin Films

Min-Hee Hong,Young Soo Lim,Jung-Kun Lee,Won-Seon Seo,Hyung-Ho Park,Chang-Sun Park

doi:10.1155/2013/131537

Abstract

Al-doped mesoporous ZnO thin films were synthesized by a sol-gel process and an evaporation-induced self-assembly process. In this work, the effects of Al doping concentration on the electrical conductivity and characterization of mesoporous ZnO thin films were investigated. By changing the Al doping concentration, ZnO grain growth is inhibited, and the mesoporous structure of ZnO is maintained during a relatively high temperature annealing process. The porosity of Al-doped mesoporous ZnO thin films increased slightly with increasing Al doping concentration. Finally, as electrical conductivity was increased as electrons were freed and pore structure was maintained by inhibiting grain growth, the thermoelectric property was enhanced with increasing Al concentration.

Highlights

Development of alternative energy is very important because fossil fuels are being rapidly depleted
The grain growth of Zinc oxide (ZnO) was inhibited with increasing Al concentration
The Al doping process enhances electrical conductivity via n-type dopant and pore structure reinforcement in a mesoporous ZnO structure, which acts as a grain growth inhibitor during the hightemperature annealing process

Summary

Introduction

Development of alternative energy is very important because fossil fuels are being rapidly depleted. To maintain a high thermoelectric property, factors of Seebeck coefficient, electrical conductivity, and thermal conductivity need to be controlled individually. The order of the pore structure is very important to controlling the electrical conductivity and the thermal conductivity individually because the inelastic mean free path of electrons and phonons is different. This difference is generally referred to as the phonon-glass electron crystal (PGEC) effect. Because the inelastic mean free path of an electron is longer than that of a phonon, phonons are scattered effectively in ordered mesoporous structures [3, 4]. In order to maximize the PGEC effect, a doping source with an inhibited grain growth property is used because its ordered pore structure is less prone to collapse

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Conclusion