Printed Microlens Arrays for Enhancing Light Extraction From Organic Light-Emitting Devices

The light out-coupling efficiency of organic light-emitting devices was enhanced using microlens arrays fabricated by a direct printing technique. The high surface-free energy of a glass substrate was modified through the use of a hydrophobic silane coupling agent thus achieving a high contact angle for liquid droplets. A transparent monomer mixture of multifunctional thiol and ene was employed as a lens material. The light out-coupling efficiency was improved by 30% using printed microlens arrays without altering the electroluminescent spectrum.