Inkjet‐Printed Metal Halide Perovskite Thin‐Film Field‐Effect Transistors

ABSTRACT Metal halide perovskites (MHPs) are promising semiconductor materials for thin‐film field‐effect transistors (FETs) due to their high charge carrier mobility and solution processability. Currently, MHP thin films for FETs are mostly fabricated by spin coating, a method limited by poor material utilization, non‐uniformity, and scalability issues. In this study, inkjet‐printing (IJP) is successfully introduced as a sustainable, additive technique for MHP thin‐film FET fabrication. Spin‐coated benchmark devices were first established as a performance reference achieving a mobility of 2.2 cm 2 V − 1 s − 1 and an on/off ratio of 8 × 10 6 . Two inkjet‐based strategies are investigated: full‐substrate printing and selective in‐channel printing. With the full‐substrate printing approach we could achieve 1.6 cm 2 V −1 s −1 and an on/off ratio of 2 × 10 6 , which replicates the device performance of the spin coated reference devices. In‐channel printing enables full patterning of the FET active region and significantly reduces material waste but suffers from reduced device performance due to the coffee ring effect. By scaling the printed area and effectively isolating the coffee ring, the adverse effects are successfully mitigated, enabling a substantial recovery of device performance. This study highlights the strong potential of IJP for the fabrication of MHP thin‐film FETs and provides valuable insights into overcoming current challenges. Overall, the results demonstrate that IJP is a highly promising route toward the scalable production of fully printed, high‐performance perovskite electronics.