奈米太陽能電池技術與材料

Abstract

隨著第三代太陽能電池的發展趨勢，利用少量的材料來製作高效率太陽能電池已成 為目前研究的主軸，在本計畫中，藉由發展奈米太陽能電池技術與材料，可為上述問題 提供有效的解決方法，我們預計研究三項主要的奈米結構技術及材料，並應用這些技術 的整合發展一些新穎的概念性元件，探討奈米結構介面的物理機制，對於奈米物理及太 陽能電池研究將很有幫助。這三項主要方向為(a)發展晶矽奈米結構製程技術，奈米結 構具有很強的光侷限的特性，藉由製作分析奈米洞、奈米柱陣列的矽基板，並搭配鈍化 處理的研究，以製作矽基奈米太陽能電池；(b)研究透明導電性奈米材料，埋入薄膜電 池輔助電流的收集，並利用奈米結構寬頻譜的收光特性，可提升元件的光學吸收能力； (c)發展有機與非有機混合式太陽能電池，利用有機材料低製程成本的優點結合高載子 遷移率的矽奈米結構基板，作為未來新穎太陽能電池的研究。此外，我們亦將架設可分 析奈米尺度下光電特性的(d)近場光電流量測系統(NOBIC)，該技術有助於提升台灣對奈 米結構太陽能電池分析的水準。 在本計畫的執行過程中，我們預期整合此三項關鍵技術的研究能力，發展新穎的奈 米元件與課題：(1)薄矽奈米太陽能電池與表面鈍化、(2)量子點太陽光譜轉換電池、(3) 埋入式電極光伏元件、(4)鑲嵌式矽基與有機材料混合式電池及(5) 奈米銀太陽能電 池。這些課題整合奈米結構的光學侷限能力、電荷收集能力、量子點光譜轉換的特性及 表面電漿散射特性，可有效提升太陽能電池的轉換效率，再利用本計畫所將架設的變波 長近場光電流量測系統，分析這些新穎奈米元件的光電特性，並搭配實驗室過去三年已 建立的奈米光性與電性的模擬技巧來提升研究的深度與對材料及元件的瞭解。

As the development of photovoltaics enters the 3rd generation, achieving high-efficiency photoelectric conversion with low material consumption becomes a prerequisite for solar cells. In this proposal, we show that nano-technologies and materials could offer a timely solution to such a daunting task. We propose to develop and intermix three core technologies and materials, where novel device concepts and interface physics are of great interest to both photovoltaic and nano-science communities. They include (a) crystalline-silicon (c-Si) nanotechnology (b) conductive nano-materials, and (c) organic-inorganic hybrids. Moreover, we will also establish (d) a near-field optical-beam induced current (NOBIC) system based on the scanning near-field optical microscopy (SNOM) to enable nanoscale characterizations of the photoelectric conversion process in these novel devices. First, the c-Si nanotechnology permits sufficient light trapping at an ultra-thin wafer thickness, ~5μm. The nanowire/nanohole solar cells also decouple the path of photon absorption from that of carrier collection. However surface recombination issues are detrimental and will be investigated for these devices. Second, the conductive nano-materials include indium-tin-oxide (ITO) nanostructures, silver nanowires and various metal nano-particles, etc.. These materials are tailored to serve as highly transparent embedded electrodes for thin-film solar cells, and if well designed, may give rise to plasmonic effects that enhance the power conversion efficiency further. Third, the organic process is known for its scalability and cost effectiveness. The objective in the organic and c-Si hybrids is to develop high-efficiency cells that embrace the advantages of both materials. In addition, intermixing the three core technologies also prompts the following exciting topics that require extensive knowledge of advanced device physics and interface science: (1) Si nano-solar and its surface passivation (2) Solar cells with quantum dot (QD) spectrum converters (3) Photovoltaics with embedded nano-electrodes (4) Interdigitated Si/organic hybrid solar cells (5) Plasmonic cells with Ag nanowires and particles. As it will be shown in this proposal, the involved nano-fabrication and modeling techniques are solidly founded on the fruitful research outcomes of our laboratory during the past three years, as well as the broadband international and domestic collaborations with renowned institutions and groups