含奈米粒子之先進奈米元件結構應用於太陽能電池之研究

Abstract

在本論文中，使用硒化鎘量子點和金奈米粒子，透過離子作用力建構多層太陽能電池奈米元件結構於矽基板上。並且以不同粒徑之硒化鎘量子點依序排列組成此奈米結構，用以實現寬頻吸收光譜太陽能電池。在掃描式電子顯微鏡的觀察下，證明其結構成功地生長於矽基板上。最後，此奈米元件再經過0.16 mW/cm2日光燈照射後，於各種偏壓下皆有固定的光電流增加。在本研究中，太陽能電池功率轉換效率達1.6 % (六層結構奈米元件，電極寬度為30μm，長度為0.5μm)，最大光電流為664.42 pA，光電流量體積密度為7.385×10-19 A/nm3，以及單位體積產生功率為4.256×10-23 W/nm3。經過24天，太陽能電池效率衰減了31.8%。而經過26天之後，衰減現象趨於平緩飽和。 根據實驗結果我們發現奈米元件之電極距離縮短有助於太陽能電池功率轉換效率之提升。再此同時，我們建構ㄧ個等效電路並成功地解釋奈米元件產生光電流的運作機制，我們稱之為三維「奈米蕭特基二極體」和電組陣列模型，而且HSPICE模擬結果與量測結果一致。理論上透過模擬可得到最佳化的奈米元件結構，具有較高的太陽能電池轉換效率。最後經過模擬計算此六層結構之奈米元件效率可達36.87 % 當電極距離為40 nm，而51.17 % 當距離縮短至30 nm。

In this thesis, PDDA-capped CdSe/ZnS quantum dots and Au nanoparticles are used to construct the multi-layer solar cell nanodevice structure on a silicon substrate through ionic interaction. And an ordered assembly of PDDA-capped CdSe/ZnS QDs with different diameters was employed to realize the wideband solar cell. By SEM photographic, PDDA-capped CdSe/ZnS QDs and Au NPs were successfully deposited on the silicon substrate. Finally, the proposed nanodevices were illuminated by 0.16 mW / cm2 daylight lamp. As a result, there was a constant photocurrent increment to the current measured in the dark for each voltage bias after illumination by 0.16 mW / cm2 daylight lamp. In this work, the solar cell efficiency is 1.6% (6-layered PDDA-capped CdSe/ZnS nanodevice with 60 um in width and 0.5 um in length.) The maximum photocurrent is 664.42 pA. The highest PVD (photocurrent volume density) is 7.385×10-19 A/nm3, and power volume density is 4.256 ×10-22 W/nm3. After 26 days, 31.8% decrease in solar cell efficiency. And after 26 days, the decay tended to saturate. Meanwhile, according to the experimental results, we knew that the shorter length of the nanodevice would benefit the performance of the solar cell efficiency. Furthermore, a three-dimensional“nano-schottky-diode”arrays equivalent circuit model was constructed and used to explain the photo-sensing mechanisms. Through HSPICE simulation, the higher solar cell efficiency can be obtained based on the ideal inference. In conclusion, the optimized device dimension could be chosen, and we found that the solar cell efficiency was up to 36.87 % in 6-layered PDDA-capped CdSe/ZnS QDs and Au NPs with 30 um in width and 40 nm in length. The solar cell can achieve high efficiency based on the model calculation.