Lead-free perovskite-integrated plasmonic quantum dot/As(iii) oxyiodide-poly(o-aminothiophenol)/poly(1H-pyrrole)...

Lead-free broadband optoelectronic devices are attractive candidates for next-generation photodetection technologies. Here, we report the fabrication of a multilayer KCsSnI_6-X Cl _X /AsOI/POATP/P1HP optoelectronic device comprising a mixed-halide perovskite absorber, an AsOI/poly(o-aminothiophenol) (AsOI/POATP) nanocomposite, and a poly(1H-pyrrole) (P1HP) transport layer. Structural characterization revealed that the AsOI/POATP layer forms a hierarchically porous network consisting of nanoscale domains (∼4-10 nm) with an optical band gap of approximately 2.3 eV. Incorporation of the KCsSnI_6-X Cl _X perovskite layer, possessing a band gap of ∼1.48 eV, significantly broadened the optical absorption range and extended the spectral response into the near-infrared region. The heterostructured architecture promoted efficient charge separation and carrier transport across the multilayer interfaces. Under illumination, the KCsSnI_6-X Cl _X /AsOI/POATP/P1HP device delivered a photocurrent density of approximately 0.09 mA cm^-2 at 3 V, representing a tenfold enhancement compared with the AsOI/POATP/P1HP device (0.009 mA cm^-2). The device further exhibited a responsivity of 0.4 mA W^-1 and a detectivity of 0.12 × 10⁹ Jones in the ultraviolet region while maintaining a measurable photoresponse at longer wavelengths. Notably, these performances were achieved using a glass-supported architecture without the incorporation of conventional transparent conductive oxides such as ITO or FTO. The enhanced optoelectronic performance is attributed to the synergistic integration of the mixed-halide perovskite, the AsOI/POATP nanocomposite, and the conducting polymer transport layer. These findings demonstrate a simple and cost-effective strategy for developing lead-free optoelectronic devices with broadband spectral sensitivity.