Browsing by Author "Lan, Tian-wey"

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Controlled mechanical cleavage of bulk niobium diselenide to nanoscaled sheet, rod, and particle structures for Pt-free dye-sensitized solar cells
(2014)
Ibrahem, Mohammed Aziz
;
Huang, Wei-Chih
;
Lan, Tian-wey
;
Boopathi, Karunakara Moorthy
;
Hsiao, Yu-Chen
In this study, we report a one-step process for the preparation of NbSe2 nanosheets, nanorods and nanoparticles from pristine materials under the effects of shear and friction forces. Nevertheless, simple and facile methods for the large-scale syntheses of well-defined NbSe2 nanostructures in high yield have yet to be realized and that will have a great impact in a wide range of applications. For example, developing platinum (Pt)-free and highly efficient counter electrodes is meaningful and necessary for the cost reduction of dye-sensitized solar cells (DSSCs). By integrating this approach with a simple method of thin film preparation (spray coating) allowed us to prepare large-area, conductive, semitransparent flexible thin films of NbSe2. We have used microscopic and macroscopic methods to examine the morphologies, compositions, crystallinity, and electrical and optical properties of the converted NbSe2 nanostructures. DSSCs with NbSe2 nanosheet counter electrodes (CEs) achieved a conversion efficiency of 7.73%, superior to an efficiency of 7.01% for Pt-based CEs. Our NbSe2 nanostructure provides a cost-effective CE alternative to the noble metal Pt in DSSCs.
High quantity and quality few-layers transition metal disulfide nanosheets from wet-milling exfoliation
(2013)
Ibrahem, Mohammed Aziz
;
Lan, Tian-wey
;
Huang, Jing Kai
;
Chen, Yang-Yuan
;
Wei, Kung-Hwa
Low-cost and large-area electronic applications require the deposition of active materials in simple and inexpensive techniques at room temperature; properties usually associated with polymer films. In this study, we demonstrate a simple, low-cost and environmentally friendly method for the high-yield production of two dimensional nanosheets of semiconducting transition metal disulfides, integrated with the route towards the solution-processed deposition of MoS2 and WS2 thin films. The resulting materials with high purity and no contamination or distortion in their structural and electronic properties were confirmed with different microscopic and macroscopic methods. As a proof of concept, we utilize these layered transition metal disulphide films as electron extraction layers in an inverted structure organic solar cell, prepared at relatively low annealing temperatures (<= 150 degrees C). A promising power conversion efficiency with high stability is achieved, which makes these proposed buffer layers quite attractive for next-generation flexible devices requiring high conductivity and transparency, as well as wide range of other potential applications.