製作光捕捉型矽奈米結構與單晶矽薄膜應用於異質接面矽太陽能電池

Fabrication of Light Trapping Si Nanostructure and Single-crystalline Si Thin Film for the Application of Hybrid Si Solar Cells

劉建廷(Chien-Ting Liu)

指導教授 ： 林清富

國立臺灣大學/電機資訊學院/光電工程學研究所/碩士(2015年)

https://doi.org/10.6342/NTU.2015.10879

摘要

現今能源需求量不斷攀升，使再生能源的發展受到重視。其中，太陽能可謂取之不盡用之不竭，且為綠色潔淨能源，是極有潛力的替代能源。目前主流高效率的結晶矽太陽電池市占率85%，但因為需要透過許多半導體製程方式來製作且製程程耗時，使得製作成本高昂。相對來說，有機太陽能電池具有低成本、製作快速、可撓、輕薄等優勢，但光電轉換效率較低。因此，目前許多團隊結合兩種太陽能電池各自的優點，積極開發低成本且製程快速的有機無機混成矽太陽能電池，並在製程成本、元件效率與應用性三方面著手努力，使其達到商業化。
本論文中，研究低成本之有機無機混成矽太陽能電池，結構為矽奈米結構/PEODT:PSS混成異質接面。其中，利用低成本的溶液製程之金屬輔助化學蝕刻來製作矽奈米結構，奈米結構具有良好的抗反射效果，能大幅增加太陽光的收集。首先，利用改良的金屬輔助化學蝕刻，在目前在商業化六吋單晶與多晶矽基板上製作大面積均勻矽奈米結構，並具有低反射率分別為3~6%與4~10%，此大面積均勻矽奈米結構具備未來產業導向之商業化應用的可行性。
在元件的製作與效率提升方面，利用簡單、快速和低成本的溶液製程的方式來製作矽奈米結構/PEODT:PSS混成異質接面太陽電池與提升效率。其中，設計優化塗佈之電洞傳輸層，利用高導電率的PH1000電動傳輸層搭配添加劑DMSO增加導電性，以取代傳統昂貴的N+層製作。並且利用兩步驟蝕刻之奈米洞的製作方法，降低銀材料的用量和增加奈米結構機械強度，再加上優化矽奈米洞與ITO電極接觸的接面，使效率提升到12.11%。
在元件應用性方面，製作可撓式之矽奈米洞/PEODT:PSS混成異質接面矽薄膜太陽電池。其中，利用簡單的HNA (HF:HNO3:CH3COOH)溶液蝕刻方式來製作可撓式矽薄膜。接著搭配低成本的奈米洞結構，使薄膜吸收由60%提升到90%以上，並製作成矽奈米洞/PEODT:PSS混成異質接面太陽電池，使30μm、50μm及100μm厚度之矽奈米洞/PEODT:PSS混成異質接面太陽電池效率分別提升到10.14%、11.03%及12.23%，同時也證明30μm~100μm的單晶矽薄膜能相容於並應用在矽奈米洞/PEODT:PSS混成異質接面。因此，替太陽能電池增加諸多未來新穎設計結合的應用性。
本論文中，我們成功地利用低成本溶液製程之金屬輔助化學蝕刻，來製作矽奈米結構大面積均勻矽奈米結構。並利用簡單、快速和低成本的溶液製程的方式來製作矽奈米結構/PEODT:PSS混成異質接面太陽電池與提升效率。最後，製作可撓式之矽奈米洞/PEODT:PSS混成異質接面矽薄膜太陽電池。因此，矽奈米洞/PEODT:PSS混成異質接面矽薄膜太陽電池相當具有發展潛力和應用性。

關鍵字

金屬輔助化學蝕刻 ； 有機無機混成矽奈米結構太陽能電池 ； 異質接面 ； 奈米結構 ； 奈米線 ； 奈米洞 ； 單晶矽薄膜 ； 可撓性

並列摘要

The development of renewable energy technologies has received much attention because of the continuing increase of energy demand. Among those technologies, solar energy has features of inexhaustibility and cleanness, and is the most promising alternative energy. Currently, the mainstream high efficiency crystalline silicon solar cells have 85% market share, but they need many semiconductor process and is time-consuming, resulting in hight fabrication cost. In contrast, organic solar cells have the advantage of low cost, fast production, mechanical flexibility, and light weight, but with lower power conversion efficiency. Therefore, many research groups combine the advantages of these two kinds of solar cells so as to develop low cost and fast fabrication of organic-inorganic hybrid silicon solar cells. Besides, they focus on improving in three aspects of process cost, efficiency and application, finally, to achieve commercialization.
In this thesis, we focus on research in low cost organic-inorganic hybrid silicon solar cells, and the device structure is silicon nanostructure/PEDOT:PSS hybrid heterojunction. Here, the low-cost solution-processed metal assisted chemical etching (MacEtch) is used to form silicon nanostructure. The silicon nanostructure has a good anti-refletion effect, and can significantly increase the collection of sunlight. Fist of all, the improved MacEtch is employed to fabricate uniform silicon nanostructure arrays on commercial six-inch mono-crystalline and multi-crystalline silicon wafers, having low reflection of 3~6% and 4~10%, respectively. The large area uniform silicon nanostructure has fesiblity in applications for future industry-oriented commercialization.

For device fabrication and efficiency improvement, we use simple, fast, and low-cost solution-processed method to fabricate silicon nanostructure/PEDOT:PSS hybrid heterojunction solar cells and improve its efficiency. Here, by designing and optimizing spin-coated hole transporting layer (HTL), the high conductivity PH1000 with additive DMSO is utilized to increase HTL conductivity, so as to replace traditionally expensive N+ layer formation. Besides, two-step silicon nanohole fabrication is used to decrease siliver consume and increae nanostructure robustness. Furthermore, by improving contact of ITO and silicon nanostructure, the device efficiency achieves 12.11%.
In the device application aspect, we fabricate flexible silicon nanohole/PEDOT:PSS hybrid heterojunction silicon thin film solar cells. Here, the simple HNA (HF:HNO3:CH3COOH) solution etching method is utilized to fabricate flexible silicon thn film. By texturing silicon nanohole structure, the silicon thin film absorption is increased from 60% to 90%. The flexible silicon nanohole/PEDOT:PSS hybrid heterojunction silicon thin film solar cells efficiency for 30μm, 50μm and 100μm is 10.14%, 11.03% and 12.23%, respectively. This also demonstrates that silicon thin film of 30μm~100μm is compatible with hybrid solar cell fabrication process. Thus, the flexible silicon nanohole/PEDOT:PSS hybrid heterojunction silicon thin film solar cells are promising for future applications and innovative designs.
In this work, we successfully utilize low-cost solution-processed MacEtch to form large area uniform silicon nanostructure arrays. Besides, we use simple, fast, and low-cost solution-processed method to fabricate silicon nanostructure/PEDOT:PSS hybrid heterojunction solar cells and improve its efficiency. Furthermore, we fabricate flexible silicon nanohole/PEDOT:PSS hybrid heterojunction silicon thin film solar cells. Thus, the silicon nanostructure/PEDOT:PSS hybrid heterojunction solar cells have considerable development potential and applicability.

並列關鍵字

Metal-assisted chemical etching (MacEtch) ； organic-inorganic hybrid silicon nanostructure solar cell ； heterojunction ； nanostructure ； nanowires ； nanoholes ； single crystalline silicon thin film ； flexible

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