tailieunhanh - Báo cáo hóa học: " Nanostructured titania films sensitized by quantum dot chalcogenides'

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: Nanostructured titania films sensitized by quantum dot chalcogenides | Kontos et al. Nanoscale Research Letters 2011 6 266 http content 6 1 266 o Nanoscale Research Letters a SpringerOpen Journal NANO EXPRESS Open Access Nanostructured titania films sensitized by quantum dot chalcogenides 1 1 2 2 Athanassios G Kontos Vlassis Likodimos Eleni Vassalou Ioanna Kapogianni Yannis S Raptis Costas Raptis and Polycarpos Falaras1 Abstract The optical and structural properties of cadmium and lead sulfide nanocrystals deposited on mesoporous TiO2 substrates via the successive ionic layer adsorption and reaction method were comparatively investigated by reflectance transmittance micro-Raman and photoluminescence measurements. Enhanced interfacial electron transfer is evidenced upon direct growth of both CdS and PbS on TiO2 through the marked quenching of their excitonic emission. The optical absorbance of CdS TiO2 can be tuned over a narrow spectral range. On the other side PbS TiO2 exhibits a remarkable band gap tunability extending from the visible to the near infrared range due to the distinct quantum size effects of PbS quantum dots. However PbS TiO2 suffers from severe degradation upon air exposure. Degradation effects are much less pronounced for CdS TiO2 that is appreciably more stable though it degrades readily upon visible light illumination. Introduction In recent years nanostructured materials and quantum dots QDs light harvesting assemblies have emerged as highly promising building blocks for the development of and third generation solar cells affording efficient conversion of solar energy to electricity. Among different technologies dye sensitized solar cells DSCs 1 hold great promise as an alternative renewable energy system with the advantages of low cost transparency and flexibility 2 . DSCs make use of nanocrystalline semiconducting electrodes the most common being TiO2 sensitized with molecular dyes the most efficient being polypyridyl ruthenium II complexes in order to harvest solar light. In .