To improve the efficiency of devices based on flexible substrates, nanostructuring technology has become indispensable, because planar structure causes unwanted surface reflection (about 10.4% for polymer film with refractive index n=1.6) and total internal reflection (89% for critical angle 38.7°).
Flexible plastic substrates are lightweight, inexpensive and enable roll-to-roll (R2R) mass production 1, 2, 3, so they have applications as components in next-generation optoelectronic devices such as organic light-emitting diodes (OLEDs) 1, 3, 4, 5, displays 6, 7, organic solar cells 8, 9, 10, 11 and photodiodes 2, 12.
