Systems, methods, and structures for improving the performance of thin-film electronic devices, in particular organic LEDs (OLEDs) used in lighting, are disclosed. Enhanced substrates, upon which OLED devices may be deposited, incorporate various structures for extracting light trapped in the device stack and substrate. The substrates provide an improved transparent electrode layer. Methods for forming planarized buried extraction structures to reduce disruption to the deposited device stack layers are disclosed, as are methods for providing smooth, planarized buried metal mesh conductors.