Cross-linkable deep-blue small molecular material for solution-processed organic light-emitting diodes

Abstract

The development of deep-blue electroluminescent fluorescent materials with solution-processability and small molecule has exerted a great influence on the application in organic light-emitting diodes (OLED) field. However, so far there still lack of small molecule deep-blue materials suitable for solution-processed OLEDs and its wide band gap and low carrier mobility are requisite. Notably, the poor solvent resistance of small molecule usually incurs the inter-layer corrosion while using solution process to deposit multiple layers, which would result in poor device performance. In this work, a cross-linkable deep-blue light-emitting material DPCS-DPS containing diphenylsulfone/carbazole units and styrene groups has been designed and synthesized. The hole and electron transport parts composed of diphenylsulfone/carbazole exhibited bipolar charge-transporting properties, and the styrene group exhibited good solvent-resistance after thermal cross-linking, which is beneficial for the preparation of subsequent functional layers by solution process. By using the DPCS-DPS, the non-doped OLED achieved deep-blue emission wavelength of 415 nm, and the doped device approached a maximum current efficiency of 1.19 cd A−1 and maximum power efficiency of 0.75 lm W−1.