量子點敏化太陽能電池光電極材料製備與元件性能分析

Preparation and Characterization of Photoelectrode and Application in Quantum Dots-Sensitized Solar Cells

高啟軒(Ci-Syuan Gao)

指導教授 ： 鍾淑茹

國立虎尾科技大學/工程學院/材料科學與綠色能源工程研究所/碩士(2014年)

摘要

染料敏化太陽能電池(Dye-Sensitized Solar Cells, DSSC)中的光電極材料是由TiO2和染料所組成，本研究利用膠體化學法，將CdSe量子點沉積在TiO2上(命名為TiO2@CdSe-T3/T60)，取代染料並改善染料在長波長吸收不足的缺點。此外，也以物理的方式將TiO2和CdSe量子點混合(命名為TiO2/CdSe)，分別以不同的混合方式、CdSe量子點含量及吸收範圍，探討上述變數對量子點敏化太陽能電池(Quantum Dot-Sensitized Solar Cell, QDSSC)性能的影響。研究中利用XRD、UV-Vis、FL和TEM等分析儀器，分別鑑定光電極材料的結構、光學特性、形貌以及成分組成，並組裝成QDSSC進行電性分析。研究結果顯示，兩種混合方式之樣品的吸收強度皆隨CdSe量子點含量的增加而有增強的趨勢，其中TiO2/CdSe和TiO2@CdSe-T3的吸收峰在640 nm，吸收範圍介於300~730 nm之間。TiO2@CdSe-T60樣品的吸收峰位在680 nm，吸收範圍介於300~800 nm。這三種樣品皆無放射特性。TiO2/CdSe和TiO2@CdSe-T3之形貌皆為近球形，粒徑約為5 nm，而TiO2@CdSe-T60樣品的形貌亦為近球形，粒徑約為9 nm。
元件經電性分析結果顯示，兩種混合方式所形成的元件的短路電流(Isc)都隨著CdSe量子點含量增加有增加的趨勢，但以TiO2@CdSe為光電極所得的轉換效率高於TiO2/CdSe，推測是物理混合讓CdSe量子點與TiO2之間的接觸不良所導致。空氣中熱處理也會降低轉換效率；以氮氣進行熱處理，轉換效率可大幅的提升，當CdSe量子點的添加量為40 wt%時，TiO2@CdSe-T60有最佳的元件性能，其光電轉換效率為2.01 %、短路電流(Isc)為8.64 mA/cm2、開路電壓(Voc)為0.43 V及填充因子(FF)為0.54。

關鍵字

量子點敏化太陽能電池 ； 膠體化學法 ； CdSe 量子點 ； TiO2 ； 轉換效率

並列摘要

Photoelectrode of Dye-Sensitized Solar Cells (DSSC) is assembled by TiO2 and organic dye. We use colloid chemistry method to prepare TiO2@CdSe sample and blends TiO2 with CdSe to form TiO2/CdSe sample. Those two kinds of samples are used as photoelectrode materials. The concentration of CdSe and annealing atmosphere effect are explored. The crystal structure, optical properties, morphologies and compositions are measured by XRD, UV-Vis, FL and TEM, respectively. The results show that CdSe is zinc blende structure, while TiO2 is anatase phase. Both absorbance and absorption range (300-730 nm) are increased with increasing CdSe concentrations. When prolong the reaction time to 1 h, the TiO2@CdSe-T60 sample with absorption range from 300 to 800 nm can be obtained. All sample shows that no emission intensity can be detected and the morphologies are spherical shape. The particle size is 5 nm for both TiO2@CdSe-T3 and TiO2/CdSe samples, while 9 nm for TiO2@CdSe-T60 with 680 nm absorption wavelength.
In the quantum dot-sensitized solar cell (QDSSC) performance measurement, the result shows that the Isc also increases with increasing CdSe concentrations. We also find that the TiO2@CdSe photoelectrode has better performance than that of TiO2/CdSe, due to the surface contact between CdSe and TiO2 of TiO2@CdSe is better than TiO2/CdSe. The TiO2@CdSe-T60 sample has low photovoltaic conversion efficiency (η) after anneals in air, while η is improved after N2 annealing very significantly. When the CdSe loading content is up to 40 wt%, it shows the best performance. The device performance such as η, Isc, Voc, and FF are 2.01 %, 8.64 mA/cm2, 0.43 V, and 0.54, respectively.

並列關鍵字

quantum dot-sensitized solar cell ； colloid chemistry method ； CdSe quantum dot ； TiO2 ； conversion efficiency

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