A 1-V solution-processed polymer vertical transistor with on/off current ratio higher than 2×104 is firstly demonstrated. The channel length is 200 nm. A new structure is used to perform reliable leakage control. Significant impacts of thin film morphology and metal doping effect on the leakage current of organic vertical transistors are firstly observed and recognized as two new leakage phenomena. The complete leakage control and the reliable process in our report enable polymer vertical transistors for real applications.