Photoresponsive n-channel organic field-effect transistors based on a tri-component active layer

Introducing photochromic molecules into the active layer of organic field-effect transistors (OFETs) is a direct way to implement a photoresponse nature in OFETs. However, active layer blended photoresponsive transistors based on n-type semiconductors are challenging and rarely studied, which are crucial for multifunctional organic-based logic applications. Herein, we fabricated n-channel photoresponsive OFETs based on a tri-component active layer spin-coated from the mixed solution of an n-type semiconductor (NDI2OD-DTYM2), spiropyran and polystyrene with a weight ratio of 1:1:1. The morphology of the blended films was improved by the introduction of the polymer matrix. Photochromic spiropyran molecules dispersed in the semiconductor layer could switch between the closed-ring state and ionic open-ring state flexibly under the irradiation of different wavelengths of light, and thus change the channel conductivity reversibly and modulate the OFET characteristics. Therefore, under the irradiation of alternate UV and vis light, both the device carrier mobility and current on and off ratio successfully realized a reversible switch.