A Smart Light‐Controlled Carrier Switch in an Organic Light Emitting Device

Abstract A real ON–OFF carrier switch based on a new ferrocenyl diarylethene compound (DTE‐FC) as the light‐sensitive and photoswitching layer in an organic light‐emitting device (OLED) with a multilayer sandwich structure has been prepared. This switch layer functions not only as a hole transporter but also as a good barrier block when needed, which arises from the light‐induced photochromic effect of the DTE‐FC. For the uncolored open‐ring form of DTE‐FC, no luminescence was observed despite the increase in applied voltage. On the contrary, for the colored photostationary state of DTE‐FC, which was obtained by irradiation with 365 nm light, the luminescence could be observed when the applied voltage reached 14.0 V and increased with applied voltage. Thus, the uncolored state corresponds to the OFF state of luminescence and the photostationary state corresponds to the ON state. The two states can be interconverted by control of the UV and visible light (>500 nm) irradiation.