Here, a novel strategy is reported to develop polymer field effect transistors using ethanol, propanol, and butanolthe most environmentally benign solvent except wateras processing solvents. From such environmentally benign processes, for the first time high-mobility (>1 cm(2) V-1 s(-1)) polymer field effect transistors are demonstrated. These mobility values realized from really green solvents exceed those of conventional hydrogenated amorphous silicon semiconductors. To achieve this 1) stable sub-microparticles of conjugated polymers dispersed in alcohols are fabricated, 2) an aldehyde-assisted surface tension-depression methodology is developed to successfully form thin films from alcohol, and 3) the structural information of alcohol-dispersed sub-microparticles of semiconducting polymers is carefully characterized.