Succinic acid as a coordination modulator for DMSO-free low-dimensional red-emitting tin perovskites

초록

Low-dimensional Sn-based perovskites have emerged as promising lead-free emitters for perovskite light-emitting diodes (PeLEDs), yet their development is constrained by the intrinsic chemical instability of Sn2+ and uncontrolled crystallization during precursor processing and film formation. Conventional dimethyl sulfoxide (DMSO)-based solvent systems introduce both dynamic coordination and solvent-induced redox activity with Sn2+, resulting in unstable precursor intermediates, uncontrolled nucleation, and defect-rich films. This inherent conflict between crystallization control and solvent-induced degradation hinders the development of a unified strategy for Sn2+ stabilization, controlled film formation, and defect suppression. To address this limitation, we introduce a DMSO-free coordination strategy using succinic acid (SA) as a bidentate modulator in a dimethylformamide (DMF)-based precursor system. The strong chelating coordination between SA and Sn2+ stabilizes iodostannate intermediates, suppressing oxidation while regulating precursor conversion kinetics. This coordination-mediated control regulates nucleation and promotes more uniform crystal growth, enabling the formation of highly crystalline PEA2SnI4 perovskite thin films with enlarged grain domains and reduced microstrain. As a result, PeLEDs fabricated from the DMF:SA system exhibit improved luminance and external quantum efficiency compared with the conventional DMF:DMSO system. Overall, this work highlights coordination-modulated precursor chemistry as a promising route toward stable and sustainable DMSO-free Sn-based perovskite optoelectronics.

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