Tuning the Electrical Property and Electronic Band Structures of Organic Semiconductors via Surface Tension

Stress engineering is an effective way to tune the performance of semiconductors, which has been verified in the work of inorganic and organic single-crystal semiconductors. However, due to the limitations of the vapor-phase growth preparation conditions, the deposited polycrystalline organic semiconductors are more susceptible to residual stress. Therefore, it is of great research significance to develop a low-cost stress engineering applicable to vapor-deposited semiconductors. In this work, we utilized the nonwetting state between water and semiconductors to provide compressive strain to the semiconductors and offset the tensile strain generated during thermal annealing. XRD and UPS measurements revealed that the water-treated films exhibited better crystal quality, lower work function (WF), and higher HOMO levels. These results highlighted the critical role of strain in modulating WF, demonstrating that compressive strain alleviates dynamic disorder and enhances intermolecular coupling. The transistors with water treatment achieved an improved mobility of 6.11 cm² V^-1 s^-1 and a better stability. This work provides a feasible, low-cost approach to introduce compressive strain, facilitating the building of high-performance organic devices.