Effect of solvent induced dielectric property modulation of poly(methyl methacrylate) insulator on the electrical and photosensing behaviour of p-channel organic transistors

We have investigated the influence of solvent dipole moment on the dielectric properties of poly(methyl methacrylate) (PMMA) gate dielectric and unravel its effect on the OFET performance, environmental stability, and photosensitivity. The device performance improved substantially upon the use of high dipole moment solvents, however, it was also observed that such solvents can exacerbate the operational stability of the transistors. A detailed investigation of polymer bulk and surface properties revealed that the choice of solvents can strongly influence its micro-molecular structure, dipolar orientation and surface chemical composition which consequently, affect the device performance and stability by controlling the leakage characteristics, capacitance density, trap formation mechanism and charge trapping behaviour at dielectric/semiconductor interface. This report illustrates the requirement of proper solvent selection to achieve high electrical performance as well as long term operational stability. Our study also demonstrates that low dipole moment solvents are more favourable in transistors for photo-detection applications.