金屬硫化物於量子點敏化太陽能電池與超級電容之應用

Metal Sulfide for Quantum Dot-Sensitized Solar Cells and Supercapacitors

陳家瑩(Chia-ying Chen)

指導教授 ： 張煥宗

國立臺灣大學/理學院/化學研究所/碩士(2011年)

https://doi.org/10.6342/NTU.2011.02428

摘要

本研究論文中，將所合成的金屬硫化物奈米材料應用於量子點敏化太陽能電池之對電極(counter electrode)及超級電容上。在量子點敏化太陽能電池部分，實驗中以硝酸銅(Cu(NO3)2)及硫化鈉(Na2S)作為起始物，利用化學浸泡沉積法(chemical bath deposition, CBD)合成CuS奈米粒子薄膜，並同時修飾於FTO導電玻璃表面，且當CBD循環數為1、5、7及15時，可分別製備出粒子、粒子堆、緞帶及帶狀之奈米材料。除此之外，研究中利用UV-Vis吸收光譜及SEM加以探討CuS薄膜表面構形之變化，另以線性掃瞄伏安法、電化學阻抗分析及反射度等方式可證明經CBD循環製成之CuS電極，具有高電催化活性、高反射度及低的電荷轉移電阻。由上述之CuS電極做為CdS/CdZnSe量子點敏化太陽能電池之對電極時，於一個太陽光強度(100 mW cm-2)照射下量測其光電轉換效率，由結果顯示，經過7次CBD循環製成之CuS電極為對電極時，所組成之量子點敏化太陽能電池具最大轉換效率可達4.71 ± 0.09 %。本研究結果證明，以CuS材料與常用之鉑奈米粒子之電極比較，其具低成本、高電催化活性、高反射度、低電荷轉移電阻、對polysulfide電解液之較佳容忍度及不易被毒化等優點。於超級電容部分，將CNT/CoS奈米材料(nanomaterials, NMs)滴於FTO導電玻璃上，作為超級電容中之工作電極(working electrode)，經由高溫鍛燒處理後，分別以Raman、XPS及晶格間距量測，由結果可知，鍛燒後CNTs/CoS NMs之晶形會改變。除此之外，依據循環伏安法之測量結果，鍛燒後之CNTs/CoS NMs電極較鍛燒前之工作電極具有較大之電化學電容性，於100及10 mV s-1之掃描速率下分別可得1000及2000 F g-1以上之電容值。就我們所知，此為首次利用簡易單次鍛燒法即可製備出具高速且高效率之CNTs/CoS電容材料，並同時可大幅增加奈米材料之電容值。

關鍵字

金屬硫化物 ； 奈米材料 ； 超級電容 ； 量子點敏化太陽能電池

並列摘要

In this thesis, I synthesized nanomaterials for fabrication of counter electrodes of quantum dot-sensitized solar cells (QDSSCs) and supercapacitors (SCs). Through a chemical bath deposition (CBD), Cu(NO3)2 and Na2S were used for the preparation of highly efficient CuS electrodes on transparent fluorine-doped tin oxide glass substrates. Varying the number of CBD cycles allowed us to obtain different types of CuS structures—namely particles, aggregates, ribbon-like structures, and belt-like structures after one, five, seven, and 15 CBD cycles, respectively. I used UV–Vis absorption spectroscopy and scanning electron microscopy to monitor the structural evolution of these CuS structures. Current–potential, electrochemical impedance, and reflectance measurements revealed that the CuS electrodes prepared after seven CBD cycles exhibited high electrocatalytic activity, high reflectivity, and low charge-transfer resistance. Under one-sun illumination (100 mW cm–2), five CdS/CdZnSe quantum dot–sensitized solar cells (QDSSCs) each featuring a CuS electrode prepared from seven CBD cycles provided maximum power conversion efficiencies of 4.71 ± 0.09%. Relative to Pt electrodes, these low-cost CuS electrodes exhibit great electrocatalytic activities, high reflectivity, low charge-transfer resistance, and excellent tolerance toward poisoning in the presence of polysulfide electrolytes. I also prepared carbon nanotubes (CNTs)/CoS nanomaterials (NMs) electrodes by depositing CNTs/CoS NMs onto fluorine-doped tin oxide glass substrates, which function as working electrodes in supercapacitors (SCs). Thermal annealing of CNTs/CoS NMs leads to the crystalline structure evolution. Evidences are supported by the measurements of Raman spectra, X-ray photoelectron spectroscopy and d-spacing. Cyclic voltammograms analysis revealed thermal oxidizing CNTs/CoS NMs electrodes exhibiting excellent electrochemical capacity than that of unannealing CNTs/CoS NMs electrodes. The values of specific capacitance over 1000 and 2000 Fg-1 were obtained at a scan rate of 100 and 10 mV s-1, respectively. To our best knowledge, it is, for the first time, demonstrated the use of annealing CNTs/CoS NMs as great promising high-rate and high efficient SCs.

並列關鍵字

CuS nanostructures ； charge-transfer resistance ； reflectance ； electrocatalytic activity ； quantum dot–sensitized solar cells ； supercapacitor ； cobalt sulfide ； nanomaterials ； carbon nanotubes

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