Molding hemispherical microlens arrays on flexible substrates for highly efficient inverted quantum dot light emitting diodes

Abstract

Microlens arrays were introduced into a QLED and the EQE of the device was enhanced by a factor of 64%.

24.1% External Quantum Efficiency of Flexible Quantum Dot Light‐Emitting Diodes by Light Extraction of Silver Nanowire Transparent Electrodes

“…The higher improvement value might result from the distribution discrepancy between the actual AgNWs network stack and the Monte–Carlo simulation–generated penetrated‐network model; better results can be further achieved if AgNWs network structure is carefully studied and designed. Figure presents the CE evolution of red FQLEDs with both vacuum and solution‐processed TCEs during the past one decade, which clearly demonstrates that our FQLED with solution‐processed AgNWs TCEs outperforms the state‐of‐the‐art FQLEDs and reaches a new efficiency level, encouraging the development of flexible light‐emitting devices.…”

“…Here, by utilizing AgNWs as flexible TCEs and the light extraction structure, we successfully demonstrate a highly efficient red FQLED based on a standard inverted structure with the maximum EQE and CE reaching 24.1% and 19.5 cd A −1 , respectively. The efficiency is improved 4.4 and 3 times for EQE and CE, respectively, compared with that of the reference QLED with glass/ITO TCEs and 1.7 times compared with that of the most efficient previous FQLED . Also, it is competitive to the reported exceedingly efficient rigid QLEDs with a similar device structure .…”

“…However, the development of high‐performance FQLEDs is much slower, lagging behind their counterparts on glass substrates. For example, the reported highest current efficiency (CE) of red FQLEDs is below 17 cd A −1 and the maximum external quantum efficiency (EQE) is about 14%, far behind 18% of the QLED on a glass substrate with similar inverted structure . The main reasons can be attributed to the inferior mechanical performance of indium tin oxide (ITO) transparent conductive electrodes (TCEs) on plastic substrates and the refractive‐index mismatch‐induced severe total internal reflection (TIR) light loss in the QLED stack …”

Light extraction from quantum dot light emitting diodes by multiscale nanostructures

“…8,9 Numerous studies have reported that the light extractions of OLEDs and QLEDs could be enhanced through introduction of internal or external light-extraction layers. [10][11][12][13][14] For example, we have demonstrated that introducing internal PEDOT:PSS grating nanostructures can effectively extract the waveguided light from QLEDs by nanoimprint lithography techniques. 15 However, the extraction of the trapped light to WG and SPP modes is more challenging since the insertion of internal structures inside the QLEDs always changes the morphology of the quantum dot emitting layers and then deteriorates the performance of the device.…”

Microlens Fabrication by Replica Molding of Electro-Hydrodynamic Printing Liquid Mold

“…Microlens and microlens array (MLA) with diameters of a few to hundreds micrometers have wide applications in various fields, including artificial compound eyes [1], light-emitting devices [2], microfluidic system [3], sensors [4], and so on. These applications require the fabrication of microlens arrays on different substrates or even on curved surfaces, thus requiring achievable microlens fabrication processes.…”