Doped polyaniline-hybridized tungsten oxide nanocrystals as hole injection layers for efficient organic light-emitting diodes

Abstract

Solution-processed tungsten oxide nanocrystals (WO₃ NCs) hybridized with a conductive polymer, polyaniline:poly(styrene sulfonate) (PANI:PSS), are introduced as a hole injection layer (HIL) in organic light-emitting diodes (OLEDs). These devices exhibited much higher current efficiency (CE) and power efficiency (PE) compared to regular devices without HILs and devices using pristine WO₃ NCs as HILs. This enhanced device performance is mainly attributed to the facilitated hole injection due to the improvement in the energy level alignment at the interface between the ITO anode and the organic semiconductor layer. Besides, PANI:PSS can efficiently reduce surface defects and enhance the film-forming properties of WO₃ NCs without affecting the device conductivity. These results suggest that PANI:PSS–WO₃ could be a promising candidate for charge injection layers in optoelectronic devices.