Ionic liquid bridging buried interface for high-performance flexible self-powered perovskite nanowire photodetectors with excellent mechanical stability

Abstract

Flexible, self-powered, carbon-based perovskite nanowire (PNW) photodetectors (PDs) are promising candidates for next-generation optoelectronics owing to their light weight, mechanical flexibility, low cost, and ability to operate without an external power supply. However, their performance and mechanical robustness are often limited by the buried SnO₂/PNW interface, where interfacial defects, unfavorable energy-level alignment, and residual strain impede charge extraction and stress relaxation, thereby increasing non-radiative recombination and accelerating degradation under bending. Herein, we report an ionic-liquid “molecular bridge” strategy using 1-butyl-3-methylimidazolium hydrogen sulfate (BMIMHSO₄) to engineer the buried interface in carbon-based self-powered PNW PDs. The BMIMHSO₄ interlayer effectively passivates interfacial defects, suppresses non-radiative recombination, optimizes energy-level alignment, and promotes interfacial stress release, thereby simultaneously enhancing device performance and flexibility stability. Rigid devices with a Glass/FTO/SnO₂/BMIMHSO₄/MAPbI₃ PNWs/PMMA/Carbon architecture deliver an outstanding linear dynamic range of 190 dB, a high responsivity of 11.52 A W⁻¹, and a detectivity of 5.45 × 10¹³ Jones, ranking among the best reported carbon-based self-powered perovskite PDs to date. Notably, the flexible BMIMHSO₄-modified carbon-based devices retain 95% of their initial performance after 2000 bending cycles, outperforming most flexible perovskite PDs employing precious-metal electrodes. This work provides a simple, air-processable buried-interface engineering route for low-cost, high-performance, and mechanically reliable flexible PNW photodetectors, accelerating their practical deployment in wearable and flexible optoelectronic applications.