SUBSTRATE FOR ORGANIC ELECTROLUMINESCENT ELEMENT, ORGANIC ELECTROLUMINESCENT ELEMENT, ILLUMINATING DEVICE, AND DISPLAY DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a substrate for an organic electroluminescent element capable of suppressing generation of dark spots and improving the light emission efficiency.SOLUTION: A substrate for an organic electroluminescent element (10) comprises: a base material body (11); an unevenness structure provided on a principal surface of the base material body (11); and a high refractive index material layer (13) formed on the unevenness structure. A light-emitting layer of an organic electroluminescent element is provided on a surface opposed to the unevenness structure, of the high refractive index material layer (13). A three-dimensional arithmetic average roughness Sa of the surface of the high refractive index material layer (13) is within a range represented by the following expression (1): 0.3 nm