Photo‐/Thermal‐Responsive Field‐Effect Transistor upon Blending Polymeric Semiconductor with Hexaarylbiimidazole toward Photonically Programmable and Thermally Erasable Memory Device

Abstract

It is shown that the semiconducting performance of field-effect transistors (FETs) with PDPP4T (poly(diketopyrrolopyrrole-quaterthiophene)) can be reversibly tuned by UV light irradiation and thermal heating after blending with the photochromic hexaarylbiimidazole compound (p-NO₂ -HABI). A photo-/thermal-responsive FET with a blend thin film of PDPP4T and p-NO₂ -HABI is successfully fabricated. The transfer characteristics are altered significantly with current enhanced up to 10⁶ -fold at V_G = 0 V after UV light irradiation. However, further heating results in the recovery of the transfer curve. This approach can be extended to other semiconducting polymers such as P3HT (poly(3-hexyl thiophene)), PBTTT (poly(2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b] thiophene)) and PDPPDTT (poly(diketopyrrolopyrrole-dithienothiophene)). It is hypothesized that TPIRs (2,4,5-triphenylimidazolyl radicals) formed from p-NO₂ -HABI after UV light irradiation can interact with charge defects at the gate dielectric-semiconductor interface and those in the semiconducting layer to induce more hole carriers in the semiconducting channel. The application of the blend thin film of PDPP4T and p-NO₂ -HABI is further demonstrated to fabricate the photonically programmable and thermally erasable FET-based nonvolatile memory devices that are advantageous in terms of i) high ON/OFF current ratio, ii) nondestructive reading at low electrical bias, and iii) reasonably highly stable ON-state and OFF-state.