利用介面處理之高效率混合型有機/矽奈米線異質接面太陽能電池

High Efficiency Hybrid Organic/Silicon-Nanowire Heterojunction Solar Cell via Interface Engineering

蔡佳縈

指導教授 ： 洪勝富 ； 孟心飛

國立清華大學/電機資訊學院/光電工程研究所/碩士(2013年)

摘要

為了達到有效節省矽太陽能電池製程成本的目的，以矽奈米線為基板的混合型有機-無機異質接面型太陽能電池為下個世代的光伏元件的發展重點，因為它具有低製程成本跟達到高效率的潛力，矽奈米線陣列可利用簡單的金屬輔助化學式濕蝕刻方法製作成大面積的奈米結構，因此在所形成的p-n介面能提升光的吸收跟載子的收集，而先前以矽奈米線為基板的混合型太陽能電池的研究發表轉換效率大約為10~11%，這是由於矽奈米線陣列提供了較大的表面面積但也造成了更多的界面缺陷產生，因而降低開路電壓以及填充因子。
在本論文中，我們開發出一種溶液製程高效率混合型有機-矽奈米線太陽能電池，在矽奈米線跟PEDOT:PSS的界面加入一有機層TAPC用以改善介面之間的缺陷、品質，並且改變了有機層PEDOT:PSS在矽奈米線上的形貌以及減少飽和暗電流因而提升開路電壓和填充因子，其元件轉換效率可達13%。有機層TAPC在矽奈米線基板以及PEDOT:PSS的界面形成一電子阻擋層減少了介面間載子的復合因而提升了少數載子的生命週期，並且透過X-ray光電子能譜儀的量測，有機層TAPC能阻止PEDOT:PSS在矽基板上強烈的氧化反應，而氧化反應所形成的二氧化矽會阻擋載子的傳輸，因此，有機層TAPC提供一個良好的介面處理使得混合型太陽能電池能有更好的元件表現。

關鍵字

混合型太陽能電池 ； 異質接面 ； 矽奈米線

並列摘要

Hybrid organic-inorganic heterojunction solar cells based on silicon nanowires (SiNWs) are promising candidates for next-generation photovoltaics owing to potentials for low fabrication cost and high efficiency. The SiNW array, fabricated by a simple metal-assisted wet chemical etching method, produces a large surface-area-to-volume ratio, hence allowing efficient light harvesting and charge collection via the formation of a core-sheath p-n junction. However, previously reported power conversion efficiencies (PCEs) are approximately capped at 10~11%, which is largely depicted by the interface defect densities that limit the open-circuit voltage (Voc) and fill factor (FF).
In this work, we introduce a solution-processed, intermediate 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC) layer to mitigate the interface recombination loss for hybrid heterojunction solar cells consisted of SiNWs and polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). The power conversion efficiency reaches a record 13%, which is largely ascribed to the modified organic surface morphology and suppressed saturation current that boost the open-circuit voltage and fill factor. The insertion of TAPC clearly increases the minority carrier lifetime due to large electron barrier presented at the interface. Furthermore, X-ray photoemission spectroscopy confirms that TAPC can effectively block the strong oxidation reaction occurred at the PEDOT:PSS-silicon interface, which improves the device characteristics and promises improvement for reliability. The learning presented in this work point detailed directions for interface engineering towards the attainment of highly efficient hybrid photovoltaics.

並列關鍵字

Hybrid solar cell ； Heterojunction ； Silicon nanowires

參考文獻

[1] Service, R. F. Science 2008, 319, 718.

[2] Fthenakis, V. M.; Kim, H. C. Sol. Energy 2011, 85, 1609−1628.

[5] Fthenakis, V. M.; Kim, H. C. Sol. Energy 2010, 85, 1609.

[9] Zhang, F.; Song, T.; Sun, B. Nanotechnology 2012, 23, 194006.

[12] He, L.; Rusli; Jiang, C.; Wang, H.; Lai, D. IEEE Electron Device Lett. 2011, 32, 1406−1408.