Low-Temperature Fabrication of Platinum Nanostructures and Novel Platinum/Graphene Nanocomposites for Dye-Sensitized Solar Cells
Eric Wei-Guang Diau
|關鍵字:||染料敏化太陽能電池;催化;對電極;Dye-Sensitized Solar Cells;catalyst;counter electrode|
在本論文的第二部分，利用電化學循環伏安法沉積均勻的鉑奈米結構於覆有石墨烯之FTO基材表面，發展出新穎的鉑/石墨烯複合材料作為對電極觸媒。我們發現，藉由含氧官能基與缺陷結構的增加，石墨烯薄膜經後處理可改善其催化活性。將鉑/石墨烯複合材對電極進行元件光電轉換效率量測，其達到8.0%，略高於傳統鉑對電極的7.9%，此效能的提升主要來自於FF的增加。有別於單純石墨烯或鉑組成之對電極，鉑/石墨烯複合材對電極具有更多的優點與發展性，其中由電化學交流阻抗量測的結果顯示，其電荷轉移阻抗僅1.8 Ω，相對於傳統鉑對電極3.5 Ω及石墨烯對電極23 KΩ，更凸顯出其優異的催化特性，是非常有潛力的對電極材料。|
Polyol synthesis is a successful method to generate metal nanostructures with well deﬁned and controllable shapes. Here we report the fabrication of Pt nanostructures as transparent counter electrode (CE) for dye-sensitized solar cells (DSSC) via a dip-coating process suitable for flexible devices. A self-assembled monolayer (SAM) of Pt nanostructures was fabricated by linking Pt nanoparticles with thio functionalized transparent conducting oxide (TCO) substrate. Scanning electron microscope (SEM) top-view images show the Pt nanoparticles homogeneously distributed on the surface of a ﬂuorine doped tin oxide (FTO) conductive glass. Ttransmission electron microscopic (TEM) cross-section images reveal that the Pt nanopaticles are highly crystalline and self-organized on the substrate with a uniform size of 2 nm in diameter. The DSSC device made of SAM CE and optimized TiO2 photoanode attained an overall power conversion efficiency 9.2% on indium tin oxide (ITO) substrate, which is slightly higher than the device with a conventional thermal cluster Pt (TCP-Pt) CE on FTO substrate (9.1%) ；the device made of SAM CE on FTO substrate gives the efficiency 9.0%. As second part of this thesis, a novel structure of Pt/Graphene nano-composite was developed as CE materials for DSSC applications. Using cyclic electro-deposition (CED) approach previously developed in this laboratory, Pt nanostructures were deposited uniformly on a graphene thin film, dispersed on the surface of FTO substrate. Post-treatments of graphene nanosheets to increase the amount of oxygen-containing functional groups and the defect sites were performed to improve the catalytic activity. In our study, the device incorporating Pt-grafted graphene CE showed a power conversion efficiency 8.0%, which is slightly higher than that of a device made of conventional TCP-Pt CE (7.9%), due to an improvement of FF. The CEs made of Pt/Graphene composite are superior to other electrodes that consist solely of graphene or Pt ﬁlms. Based on the results obtained from the impedance spectral measurements, the charge transfer resistance of Pt/Graphene CE is 1.8 Ω, which is smaller than that of TCP-Pt CE (3.5Ω) and that of graphene CE (23KΩ). Our results indicate that the Pt/Graphene composite materials have excellent electro-catalytic performance, perfectly suitable for use as CE for DSSC.
|Appears in Collections:||Thesis|