Riedel Boris, Kaiser Inga, Hauss Julian, Lemmer Uli, Gerken Martina
Light Technology Institute, Karlsruhe Institute of Technology, Kaiserstrasse 12, D-76131 Karlsruhe, Germany.
Opt Express. 2010 Nov 8;18 Suppl 4:A631-9. doi: 10.1364/OE.18.00A631.
We present low-cost texturing methods to produce different surface roughnesses on glass substrates. Using sand blasting, abrasion and wet etching we achieve roughnesses of about 50 nm to 250 nm (root mean squared roughness Rq). These textured substrates are used as extraction elements for guided modes and substrate modes in organic light-emitting diodes (OLEDs). We evaporate 50 nm of the high index material Ta₂O₅ on the textured substrate, which acts as waveguide layer, and flatten it with the transparent photoresist SU-8. On top of that, we fabricate indium tin oxide (ITO)-free OLEDs, which are characterized by electroluminescence and photoluminescence measurements. The devices with rough interfaces obtain an up to 37.4% and 15.5% (at 20 mA/cm²) enhanced emission and it is shown that the enhancement is due to an increased outcoupling efficiency.
我们提出了低成本的纹理化方法，以在玻璃基板上产生不同的表面粗糙度。通过喷砂、研磨和湿法蚀刻，我们实现了约50纳米至250纳米（均方根粗糙度Rq）的粗糙度。这些纹理化基板用作有机发光二极管（OLED）中导模和基板模的提取元件。我们在纹理化基板上蒸发50纳米的高折射率材料Ta₂O₅，其作为波导层，并用透明光刻胶SU-8将其平整化。在此之上，我们制造了无铟锡氧化物（ITO）的OLED，并通过电致发光和光致发光测量对其进行表征。具有粗糙界面的器件在20 mA/cm²时发射增强高达37.4%和15.5%，并且表明这种增强是由于外耦合效率的提高。
