Bulk Heterojunction Optoelectrical Switching Devices Fabricated Using Nonfullerene Acceptor Y6: Aggregation-Induced Emission Polymer Blend Active Layers

By using poly {[9,9-dioctyl-9H-fluorene]-alt-(1,1,2,2-tetra-phenylethene)} (POFTPE) as an electron donor, and Y6 (or C60) as electron acceptor, solution-processed bulk heterojunction optoelectronic switching devices with a configuration of ITO/POFTPE:Y6(C60)/ITO, which can respond to both the optical and electrical stimuli, have been successfully fabricated. Both the electron transfer and energy transfer from POFTPE to Y6 will occur simultaneously in the blends system under light illumination, while no energy transfer between POFTPE and C60 occurs, expect for electron transfer. Both the ITO/POFTPE:Y6/ITO and ITO/POFTPE:C60/ITO devices show typical nonvolatile rewritable memory effect in the dark or under light illumination. Upon illumination with different wavelength lights, the switching bias window (Δ|VON-VOFF|), switching-on voltage and the ON/OFF current ratio of the ITO/POFTPE:Y6(5:1)/ITO device decrease with decreasing the incident light wavelength due to the increased free charge carrier concentration caused by light illumination. In contrast to the POFTPE:Y6 blends, the POFTPE:C60 blends-based device measured in the dark shows smaller switch-on voltage, ON/OFF current ratio and switching bias window under the same experimental conditions. This work shows one of the very promising strategies for exploring the nonvolatile multilevel storage by tailoring optoelectronic switching and memory performance of the materials via illumination with different wavelength lights.