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標題: | 利用載子選擇層增進有機無機混成矽太陽能電池效率 High Efficiency Organic/Nanostructured-Silicon Hybrid Solar Cell by Using Carrier Selection Layer |
作者: | Song-Ting Yang 楊松庭 |
指導教授: | 林清富(Ching-Fuh Lin) |
關鍵字: | 有機無機混成矽太陽能電池,異質接面,奈米結構,界面修飾,溶液製程,載子選擇層, organic-inorganic hybrid silicon solar cells,hetero-junction,nanostructure,interface modification,solution process,carrier selection layer, |
出版年 : | 2015 |
學位: | 碩士 |
摘要: | 現今,隨著科技的發展與進步,有限資源的消耗與能源需求不斷攀升,綠色意識因而高漲。在可再生能源中,太陽能由於能量充沛,應用廣泛,被視為未來極有潛力的替代能源候選。而目前太陽能產業中,雖以矽太陽能電池為主,但矽太陽能電池與石油燃料等發電方式相比,價格仍然偏高。考慮製作矽太陽能電池模組的成本裡,PN-junction的摻雜或表面鈍化製程,皆需要高溫、高壓等高成本且費時之儀器。因此,在未來太陽能的推廣及商業化的考量下,必須從三個重點方向作為依據:元件效率、穩定性,以及製程成本。 在本論文中,利用低成本的兩步驟金屬輔助化學蝕刻(two step metal assisted chemical etching)來形成低反射率高吸光性的奈米結構於矽基板上。藉由使用晶格方向(100)的單晶矽基板,依照金屬輔助蝕刻的方式,可以控制蝕刻出來的奈米結構為沿著(100)之垂直方向。根據沉積銀離子的時間及蝕刻的時間,亦能進一步掌控奈米結構之密度與蝕刻深度。再來將奈米結構與有機材料PEDOT:PSS結合,形成有機無機混成的異質接面太陽能電池。此方法不需使用高溫退火等高溫製程,再達到低成本的目標下,元件轉換效率亦可至10.58%。以此方式製作太陽能電池的最大優點為製程簡單,且近乎無高成本的儀器需求。 在元件效率的提升上,本論文研究了添加電子阻擋層與電洞阻擋層對於混成矽太陽能電池之提升,針對此兩種類型材料對矽基板表面進行介面改質。在低成本考量下使用溶液製成方式進行製備,溶液製程不僅可大幅簡化製程並降低成本,另一方面,也可降低矽基板在空氣中滯留時間過長,產生過厚的原生氧化物,進而影響元件特性。 在第二部分,我們比較幾種電子阻擋層添加於PEDOT:PSS與矽基板之間之結構,其元件架構分別是PEDOT:PSS/TAPC/SiNHs-Si與PEDOT:PSS /TPD/SiNHs-Si,由於這兩種電洞傳輸層都具有較高的LUMO能階,並控制其厚度,不影響PEDOT對矽基板異質接面之內建電場形成,又可對電子有阻擋的功能,降低其在表面復合的可能性,故其元件轉換效率可達到11.54%與11.39%。 第三部分,則以電洞阻擋層Cs2CO3添加於矽基板與背電極之間,其元件架構為SiNHs-Si/Cs2CO3/Ti/Ag,由於利用溶液製成方試塗佈Cs2CO3可以調變背面電極的能階(~3.5ev),可降低矽基板背面電洞的傳遞,達到類似在背面鍍上一層n+矽之結構。此結構亦能大幅降低矽基板與背電極間載子複合機率,而使效率能達到13.01%。最後,由於兩種材料並不互相衝突,再結合兩種材料後,更進一步使效率達到13.23%。 在本論文中,我們成功地使用了幾種界面修飾之方法來改善混成矽太陽能電池的載子複合與效率表現,且所有元件皆未經封裝並具有高穩定性。因此,未來將有希望應用此低成本、簡單、元件具有有高度穩定性的生產策略,來實現有機無機混成矽太陽能電池的商業化。 The development of renewable energy technologies has received much attention, because of the increased energy demand and the gradual depletion of fossil fuels. Among those technologies, solar energy has emerged as the potential candidate of alternative energy. Currently, crystalline Si solar cells dominate the photovoltaic market, but the cost of Si solar cells is still higher than fossil fuels. Most of the production cost for Si solar cell modules comes from p-n doping and surface passivation, those techniques all need high temperature, high vacuum and high cost machine. To reach the goal of solar cells commercialization, three important aspects have to be considered. Efficiency, stability, and production cost of the devices. In this dissertation, we employ the low cost technique, two step metal assisted chemical etching, to fabricate low reflectance nanostructure layer on silicon substrate. By changing the concentration of etching solution, we can fix the etching direction along (100) direction and form vertical nanostructure. The density and length of nanostructure can be desided by controlling volume ratio and etching time. Then, we formed organic-inorganic hetero-junction hybrid solar cell by bonding nanostructure with PEDOT:PSS. The fabrication without high temperature annealing, high cost machine and complicated process can reach 10.58% power conversion efficiency. For fabricating high performance hybrid solar cells, we research the influence of insert electron blocking layer and hole blocking layer in hybrid silicon solar cells. All techniques are using low cost solution process. By using solution process not only simplify the fabrication process but reduce fabrication time. Reducing fabrication time is very important in hybrid solar, because long process time cause thick native oxide on silicon surface. Then, the efficiency will decrease by thick native oxide. In second part, we compare two electron blocking layer between PEDOT:PSS with silicon substrate. The device structures are PEDOT:PSS/TAPC/SiNHs-Si and PEDOT:PSS/TPD/SiNHs-Si. Because the small lowest-unoccupied-molecular-orbital (LUMO) value (~2.0 eV) of the electron blocking layer, the electron will be blocked. Then, the recombination ratio of carriers will decrease. Above those results, the power conversion efficiency can achieve to 11.54% (TAPC) and 11.39% (TPD). In next part, the hole blocking layer Cs2CO3 is inserted between rear side silicon and metal. The device structure is SiNHs-Si/Cs2CO3/Ti/Ag. Because the combine with Cs2CO3 and metal can reduce the working of metal (~3.5ev), the hole will be blocked. The structure is similar to n+ silicon, it also can decrease the carriers recombination on rear side silicon. After interface modification, the power conversion efficiency can achieve to 13.01%. At last, we insert Cs2CO3 layer and TPD layer into hybrid solar cell structure. Because the carrier can be transported to electrode more easily, the power conversion efficiency can achieve to 13.23%。 In this work, we successfully employed the solution-processed interface modification to improve the device performance. All the devices studied were not encapsulated and showed high stability. This simple, low-cost, and high device stability process method provides a promising route for achieving commercialization of organic-inorganic hybrid silicon solar cells. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/52532 |
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顯示於系所單位: | 電子工程學研究所 |
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