We return to the history of light-emitting diodes, LEDs, but now talk about the development of organic versions, OLEDs, from the secret work of Roger Partridge to the now classic publication by Ching Tang and Steven Vanslyke at Eastman Kodak. Through the 1990s, more and more colors were added, so by the mid-1990s, the first commercial OLED product was marketed by electronics firm Pioneer. We also distinguish between passive and active matrix OLEDs.Support the show Support my podcast at https://www.patreon.com/thehistoryofchemistry Tell me how your life relates to chemistry! E-mail me at steve@historyofchem.com Get my book, O Mg! How Chemistry Came to Be, from World Scientific Publishing, https://www.worldscientific.com/worldscibooks/10.1142/12670#t=aboutBook