This is the author accepted manuscriptData availability: Source data are provided with this paper. Additional data related to this work are available from the corresponding authors upon request.Code availability statement: All codes (software) used in the calculation and visualization are publicly available and the condition of their usage in the publication is an appropriate citation.The engineering of tin halide perovskites has led to the development of p-type transistors with field-effect mobilities of over 70 cm2 V-1 s-1 . However, due to their background hole doping, these perovskites are not suitable for n-type transistors. Ambipolar lead halide perovskites are potential candidates, but their defective nature limits electron mobilities to around 3-4 cm2 V-1 s-1, which makes the development all-perovskite logical circuits challenging. Here, we report formamidinium lead iodide perovskite n-type transistors with field-effect mobilities of up to 33
cm2 V-1s-1 measured in continuous bias mode. This is achieved through strain relaxation of the perovskite lattice using a methyl ammonium chloride additive, followed by suppression of undercoordinated lead through tetramethyl ammonium fluoride multidentate anchoring. Our approach stabilizes the alpha phase, balances strain, and improves surface morphology, crystallinity, and orientation. It also enables low-defect perovskite–dielectric interfaces. We use
46 the transistors to fabricate unipolar inverters and eleven-stage ring oscillator
