Random wrinkle structures for spectrum preserved warm white organic light emitting diodes

Surface wrinkles of mesoscopic size were formed by a single photocuring process of an in-house synthesized linear liquid pre-polymer. The linear relationship between the amplitude and the period of the wrinkles indicates the presence of constant compressive strain during the wrinkling process. The stiffness ratio of the hard film to the soft foundation decreases as the initial film becomes thinner, providing a quantitative measure for estimating the wrinkle size. As an application, mesoscopic wrinkles were investigated as optical structures for enhanced light outcoupling and angular spectral stability of red, green, blue, and white organic light emitting diodes.