Low Work Function Surface Modifiers for Solution-Processed Electronics: A Review

Interfaces with a low work function are crucial to electron injection and collection in semiconducting devices such as diodes and transistors, and many types of surface modifiers have been developed to tailor the work functions of electronic devices. In this review, the basic and working mechanisms of low work function surface modifiers covering the surface dipole, low intrinsic bulk work function, doping, and self-doping are described. Efficient solution-processed surface modifiers developed lately to modify target surfaces are described and recent development of solution-processed semiconducting devices including organic (quantum dots and perovskite) solar cells, light-emitting diodes, field-effect transistors, and organic photodetectors is summarized. Finally, the prospects and strategies to produce efficient and reliable low work function modifiers for solution-processed semiconducting devices compatible with low-cost fabrication techniques such as printing are presented.