| 摘要: | 本研究結合雷射直寫與無電鍍技術應用於金屬透明電極之製作。因雷射光的高斯光束能量分布，強度由中間向周圍遞減，所造成溫度梯度與Marangoni effect現象，使雷射燒結的金屬線輪廓中間低兩旁高的形貌。本研究的第一部份在探討無電鍍方式是否能修補此一不均形貌。結果顯示無電鍍前後其表面形貌雖然相似，但橫截面的量測顯示兩邊與中間的高度差隨無電鍍的時間拉長而變小，所以無電鍍確可修補部分因高斯光束造成的高差問題。
第二部份使用實驗室自行合成之金屬離子複合物硝酸銀和聚乙烯醇薄膜，以雷射直寫技術形成圖案晶種，進行電鍍製作金屬網格。聚乙烯醇能螯合銀並且經由自身得失電子能將銀離子還原銀原子，過程中加熱可以增加其還原速度，且此金屬複合物有較好的成膜性。在附著力的部份，使用聚乙烯醇能增加與基板的附著力，使後續無電鍍銅也有良好的附著性。
第三部份將金屬網格應用於透明電極，金屬銅銀網格片電阻約1 Ω/ sq透光度大於80%，由於無電鍍後的金屬網格高度約在一微米左右，仍在製作於有機光電元件時，容易刺穿有機薄膜層。我們利用聚醯亞胺溶液將玻璃基板上的金屬網格嵌入至軟性基板中，製作成低表面粗糙度之可撓嵌入式金屬網格電極，並且進行往復撓曲測試，在彎曲半徑6 mm下，持續10000次彎曲，片電阻變化約增加20%。
;In this study, both techniques of laser direct writing and electroless deposition are applied to the fabrication of flexible metal-mesh transparent electrodes. Due to the Gaussian distribution of the laser beam, the intensity of laser energy decreases gradually from the middle to the periphery, resulting in transversal temperature gradient and the Marangoni effect, which makes the crosswise profile of laser-sintered metal wire with uneven height profile, lower in the middle and higher at the two ends. Thus, the first part of this study explores whether electroless deposition can repair this uneven morphology. Results show that although the surface morphology before and after electroless deposition looks similar, the cross-sectional profile measurement shows that the height difference between the middle and the two ends becomes smaller. Hence, electroless deposition is a practical solution for repairing contour defects caused by Gaussian laser beam.
The second part of this study focuses on employing the electroless deposition technique to grow metal-mesh electrode from a glass substrate with an initial laser-direct-write seed pattern. The metal seeds are generated from a spin-coated composite thin film, synthesizing from silver nitrate (AgNO3) and polyvinyl alcohol (PVA) solutions, by laser direct write. PVA is capable of chelating silver ion and the silver ions are reduced to silver atoms via gaining and losing electrons as subjected to laser irradiation. In addition, the generated heat accelerates the reduction speed. The PVA/AgNO3 composite exhibits better film-formation property and the use of PVA increases the film’s linkage to substrate. Subsequently, that leads to good adhesion of the electrode to the glass substrate.
The resultant metal-mesh electrode, consisting of silver and copper, has sheet resistance about 1 Ω/sq and transmittance greater than 80%. But the height of the mesh line is about 1 micron which is too high to penetrate organic thin films in an organic device, where the film thicknesses are ranging from several tens to hundreds nanometers. Thus, in the third part of this study, we embed the electroless deposited electrode into a polyimide (PI) substrate as an embedded flexible electrode. Consequently, the surface roughness of the embedded electrode is less than 10 nanometers. The reciprocating bending test shows that, even under a small bending radius of 6 mm, there is only a 20% of increase in sheet resistance after 10000 cycles of bending. |
