New application of AIEgens realized in photodetectors: Reduced work function of transparent electrodes and much improved performance

Highly sensitive organic photodetectors were achieved by tuning the work function of transparent electrodes using two AIEgens with different ionic side chains. With the insertion of AIE molecules, their projected detectivity (D*) was enhanced by over one order of magnitude, which was accompanied by a fast response speed and a large linear dynamic range. The devices exhibited the ability to effectively detect weak light with intensity less than 10 pW cm², which is clearly superior to traditional silicon photodetectors. The AIE molecules developed a good energetic match to facilitate photocurrents, and the non-conjugated ionic impeding effect blocked the electrons from transferring to the interface under dark conditions and lower dark currents, which significantly contributed to the high detectivity of the devices. This study indicates that high performance organic devices could be achieved by jointly controlling conjugation associated aggregation and the quantity and state of ions on the electrode surface, thus providing a new application for AIEgens.