We use organic light-emitting diodes (OLEDs) for new applications in neuroscience. OLEDs can be structured to cell-sized pixels and fabricated on soft, flexible plastic films, which makes them ideal for implants and on-skin wearable light sources. In our lab, we tailor the properties of OLEDs towards specific bio-applications. This particularly means making devices flexible, structuring to very small pixels (10 - 100 µm), increasing light intensity at low voltages, improving OLED speed, adjusting the emission spectrum, and shaping emission into forward direction. We have used OLEDs for optogenetics and for functional imaging of neuronal signals.