Doped crystalline thin-film deep-blue organic light-emitting diodes

High carrier mobility in organic thin films is beneficial for reducing the operation voltage, decreasing energy loss, and improving the light emission of organic light-emitting diodes (OLEDs). However, it is a persistent challenge to employ well-developed high-mobility organic semiconductors for fabricating OLEDs with sufficient light output. Here, we report a new type of light-emitting device, doped crystalline thin-film OLEDs (C-OLEDs). The as-fabricated devices consisting of a wide-band-gap host material exhibit strong deep-blue emission (Commission International de L'eclairage (CIE) coordinates of (0.158, 0.034), 1000 cd m(-2) at 4.1 V). Owing to the high mobility of the crystalline host matrix, the doped C-OLEDs achieve high photon output, a low driving voltage and a low ratio of Joule-heating-related series resistance energy loss, realizing a prominent improvement compared to all previously reported amorphous deep-blue OLEDs with high external quantum efficiency (EQE).