以溶膠凝膠法於室溫下製備氧化錫薄膜並與奈米銀線複合製備透明導電薄膜

Abstract

透明導電薄膜是光電元件的重要組成，而目前最常被使用的材料為氧化銦錫。然而，受限於他們固有的脆性及高耗能製程，使他們難以被應用在可撓式元件或是不耐高溫的材料上。奈米銀線因為具有卓越的導電度及透光度，同時又提供良好的撓曲性，被視為是可以取代氧化銦錫的重要材料。在此篇研究中，我們透過複合溶膠凝膠法製備的氧化錫薄膜以及噴塗的奈米銀線，成功於室溫下製備新穎的透明導電薄膜。我們首先使用高反應性的前驅物—異丙醇錫，在室溫下以溶膠凝膠法成功製備了導電且具有高穿透度的氧化錫薄膜。接著，我們將此氧化錫薄膜包覆在噴塗好的奈米銀線薄膜上製備氧化錫/奈米銀線複合透明導電薄膜。在被包覆之後，奈米銀線膜的片電阻大幅下降，這是因為氧化錫在成核時產生的毛細力會將相鄰的銀線給綁在一起，進而降低銀線間的接觸電阻。除此之外，我們發現透過雙氧水前處理，氧化錫薄膜得以更均勻的覆蓋住銀線的表面，因而使所需的氧化錫薄膜厚度下降，提升複合膜之穿透度。較薄的膜厚也預期可以使複合膜的可撓曲性提升。另外，穩定度不佳是奈米銀線在實際應用上的主要限制。在被氧化錫薄膜均勻覆蓋之後，奈米銀線導電薄膜的穩定度也得以大幅提升。此氧化錫/奈米銀線複合透明導電薄膜可望被應用在下一世代的光電元件中。

Currently, indium tin oxide (ITO) is the most widely used material for transparent conductive films (TCF), an essential component of optoelectronic devices. However, the inherent brittleness and high-energy processes of ITO have hindered its applications in flexible devices or those involving sensitive materials. In this research,we demonstrated a novel room temperature-processable TCF as an advantageous alternative to ITO by combining a sol-gel SnOx film with a sprayed silver nanowires(Ag NWs) film, which are known to offer excellent flexibility with high conductivity and transparency. By using a highly reactive precursor, tin isopropoxide (TIP), electrically conductive and highly transparent SnOx thin films were successfully fabricated from a room-temperature sol-gel process, which were then used to encapsulate sprayed Ag NWs films into SnOx/Ag NWs composite films. Upon the SnOx encapsulation, the sheet resistance of the Ag NWs TCF dramatically decreased from the pristine value, because the capillary force originated from the nucleation of the sol-gel SnOx phase bound adjacent Ag NWs together to reduce their contact resistance. Additionally, we discovered that the required thickness of the SnOx encapsulating layer could be significantly reduced, thereby increasing optical transparency of the SnOx/Ag NWs composite films, by introducing a hydrogen peroxide pretreatment to the sprayed Ag NWs layer, which enabled uniform coverage of the SnOx phase over the Ag NWs. The thinner SnOx film was also expected to provide better flexibility. Importantly, such uniformly encapsulated Ag NWs films showed substantially improved stability over their unencapsulated counterparts, addressing a major issue limiting Ag NWs’ practical uses. Our results provide a promising option of TCF for the next-generation optoelectronic devices.