Conjugated polymer-based organic field-effect transistors have garnered attention since the solution processability of the semiconductor material raises the possibility of lower device fabrication costs, and considerable progress has been made on achieving high mobility systems. Further improvements in charge carrier mobility while using non-specialized deposition techniques and minimizing the volume of semiconductor used in the fabrication process are important considerations for practical implementation. Here, a method of fabricating devices is disclosed that uses a technique (for example, a scalable blade-coating technique) to cast polymer thin film devices from blend solutions with one component being the polymer semiconductor and the other being a commodity polymer. Even when mixing the semiconducting polymer with 90% polystyrene by weight, an average mobility of 2.7±0.4 cm2V−1s−1 can be obtained.