Alkylammonium passivation for 2D tin halide perovskite field-effect transistors†

Abstract

Tin (Sn) halide perovskites have shown significant potential as channels for field-effect transistors (FETs) due to their low effective mass, reduced Fröhlich interaction, as well as lead-free composition, a requirement for electronic components. However, their inherent instability has limited their practical application. Here, we reveal that alkyl ammonium additives of appropriate size can efficiently passivate A-site defects in two-dimensional (2D) Sn halide perovskites, thereby promoting ideal octahedral formation and enhancing hydrogen bonding between A-site and X-site components. These effects lead to improved structural stability, as evidenced by enhanced crystallinity, reduced non-radiative recombination, and decreased Sn oxidation. FETs incorporating perovskites with alkylammonium cations of optimal chain length and multiple functional groups–specifically, propane-1,3-diammonium iodide–exhibit superior performance metrics, including a maximum field-effect mobility of 2.6 cm² V⁻¹ s⁻¹, an on/off current ratio exceeding 10⁶, and a threshold voltage approaching 0 V.