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Báo cáo hóa học: " One-step synthesis of PbSe-ZnSe composite thin film Seishi Abe"

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: One-step synthesis of PbSe-ZnSe composite thin film Seishi Abe | Abe Nanoscale Research Letters 2011 6 324 http www.nanoscalereslett.eom content 6 1 324 o Nanoscale Research Letters a SpringerOpen Journal NANO EXPRESS Open Access One-step synthesis of PbSe-ZnSe composite thin film Seishi Abe Abstract This study investigates the preparation of PbSe-ZnSe composite thin films by simultaneous hot-wall deposition HWD from multiple resources. The XRD result reveals that the solubility limit of Pb in ZnSe is quite narrow less than 1 mol with obvious phase-separation in the composite thin films. A nanoscale elemental mapping of the film containing 5 mol PbSe indicates that isolated PbSe nanocrystals are dispersed in the ZnSe matrix. The optical absorption edge of the composite thin films shifts toward the low-photon-energy region as the PbSe content increases. The use of a phase-separating PbSe-ZnSe system and HWD techniques enables simple production of the composite package. Introduction Quantum-dot solar cells have attracted much attention because of their potential to increase conversion efficiency 1 . Specifically the optical-absorption edge of a semiconductor nanocrystal is often shifted due to the quantum-size effect. The optical band gap can then be tuned to the effective energy region for absorbing maximum intensity over the solar radiation spectrum. Furthermore quantum dots produce multiple electronhole pairs per photon through imp act ionization whereas bulk semiconductors produce one electron-hole pair per photon. Wide-gap semiconductor sensitized by quantum dot is a candidate material for such use. The quantum dot supports absorbing visible and near-infrared light. Up to now various nanocrystalline materials InP 2 CdSe 3 CdS 4 5 PbS 6 and Ge 7 have been investigated as the sensitizer for TiO2. Alternatively a wide-gap semiconductor ZnO is also investigated since the band gap and the energetic position of the valence band maximum and conduction band minimum of ZnO are very close to that of TiO2 8 . Most of these composite .