刮刀製程大面積混合式有機/矽基太陽能電池

Abstract

混合式有機/矽基太陽能電池有低溫製程、低成本以及薄型可彎性的優勢，是為太陽能光電產業下個世代的趨勢。本實驗室長期致力於增加太陽能電池最大效率研究，但要成為實用性的輕薄混合式太陽能電池，太陽能電池的照光面積擴大，勢必成為未來發展的重點。在本論文中，將引進刮刀製程製作大面積太陽能電池，擴大製作太陽能電池的有效面積，從1x1 cm2 有效面積擴展至10x10 cm2的大面積太陽能電池，同時讓擴大面積的損耗最小化，目標將作出有效面積10x10 cm2的六吋混合式太陽能電池。 在本論文中，首先我們將奈米碳棒(Carbon nanotube)參雜在PEDOT:PSS中做為高導電高穿透的電洞傳輸層，我們以刮刀製程測試了參雜奈米碳棒的PEDOT:PSS其特性與參數，並且使用表面活性劑(Surfactant)與乙醇(Ethanol)做優化。在進行表面活性劑優化後的太陽能電池元件，在刮速為200mm/s、1x1 cm2有效面積下，元件轉換效率達到了13.0%。並且我們優化銀電極結構修正遮光比例，同時透過刮刀控制成膜均勻性將有效面積擴大至2x2 cm2，最好的效率參數在1wt%的表面活性劑、10%遮光面積以及400mm/s刮速下，達到13.5%的高轉換效率。最後，我們在6吋矽基板上測試了刮速以及膜厚用於更大面積的太陽能電池結構，初步結果顯示，10x10 cm2有效面積轉換效率達到6.9%，猜測是受到銀電極結構的限制。

Hybrid organic/ silicon solar cells employ low-temperature and solution processes and is compatible to be fabricated on bendable and thin substrates, making them promising candidates for future photovoltaic industry. However, scalability of hybrid solar cells has been limited by the uniformity of the organic thin film. In this work, we have developed a blade coating technique to expand the active area of the hybrid solar cells, from 1x1 cm2 up to 10x10 cm2 while minimizing the power loss upon scaling. First, an carbon-nanotube (CNT) doped poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) is employed as the hole conducting material for its high transparency and conductivity. The properties of CNT-doped PEDOT:PSS against the blade coating speed are tested, followed by the material modifications using surfactant and ethanol. By optimizing the amount of surfactant, we achieve a power conversion efficiency of 13.0% on a 1x1 cm2 device at the 200 nm/sec coating speed. Second, we scale up the cell area to 2x2 cm2 by optimizing the shadow ratio of the frontal silver grid, while controlling the uniformity of the film thickness at proper coating speed.

An excellent PCE of 13.5% was achieved on the 2x2 cm2 device using 1wt% surfactant, 10% shadow ratio and 400 mm/s blade coating speed, showing an PCE enhancement factor of 13.4% compared to the spin coating process. Finally the film thickness and blade coating speed have been tested on a 6-inch silicon wafer for therealization of large-area hybrid solar cells. Preliminary results show that a cell with a 10x10cm2 active area exhibits a PCE of 6.9% possibly limited by the Ag grid design.