Patent ID: 7955531

Claim:
A method of preparing a light extraction encapsulant sheet, comprising the steps of: A) providing an encapsulant block comprising a polymeric encapsulant material; and B) forming a patterned encapsulant region having an exterior patterned encapsulant surface on a surface of said encapsulant block; wherein said step of forming said patterned encapsulant region comprises: a) forming a first recess set comprising at least one first recess; b) filling said first recess with a first recess filler; c) optionally, forming a second recess set comprising at least one second recess; and filling said second recess with a second recess filler; wherein at least one of said first recess set and said second recess set has a pattern wherein: said pattern is a periodic pattern, said pattern has a feature size, in at least one lateral dimension, of at least 5 nanometers and no more than 5,000 microns; said periodic pattern has a period, in at least one lateral dimension, of at least 10 nanometers and no more than 5,000 microns; said first recess has a maximum recess depth of at least 25 nanometers and no more than 10,000 microns; said second recess has a maximum recess depth of at least 25 nanometers and no more than 10,000 microns; at least one of said first recess and said second recess has a recess opening coincident with said exterior patterned encapsulant surface; and said first recess filler differs in refractive index from at least one of said second recess filler and said encapsulant material by at least 0.001 and no more than 3.0.