Plasmon-Mediated Wavelength-Selective Response Enhancement in Narrowband Perovskite Photodetectors

Charge-collection narrowing (CCN) enables filter-free narrowband photodetection in perovskite devices but requires thick active layers to suppress short-wavelength photons, limiting the photocurrent. Herein, through strategically designing the composition, size, and shape of metallic nanoparticles (MNPs) to enable precise regulation of their localized surface plasmon resonance (LSPR) bands, which coincide exactly with the targeted narrowband response ranges, the penetrated long-wavelength incident photons have strongly coupling interaction with the electromagnetic field around MNPs to effectively improve the light absorption by near-field enhancement-induced excitation (NFEE) effect, resulting in the significant photocurrent enhancement. Based on the patterned-ITO glass substrates decorated with silver nanoparticles (AgNPs), gold nanoparticles (AuNPs), and gold nanorods (AuNRs), respectively, the lateral-type photoconductive CCN photodetectors (PDs) with MAPbX₃ (X = Cl, Br, and I) microcrystalline films were successfully constructed. The MAPbCl₃-AgNPs, MAPbBr₃-AuNPs, and MAPbI₃-AuNRs CCN PDs showed the peak responsivity as high as 171.1 A W^-1@410 nm, 269.1 A W^-1@550 nm, and 452.7 A W^-1@830 nm under the bias voltage of 5 V, respectively, along with full-width at half-maximums (FWHMs) in wavelength ranges limited to only 20-30 nm. Meanwhile, MNPs in the dark state can reduce the dark current as the electron trapping medium to facilitate the specific detectivity (<i>D</i>*) of PDs. Consequently, MAPbCl₃-AgNPs, MAPbBr₃-AuNPs, and MAPbI₃-AuNRs CCN PDs achieved an ultrahigh <i>D</i>* of 1.26 × 10¹⁴ Jones, 1.84 × 10¹⁴ Jones, and 3.13 × 10¹⁴ Jones, respectively, which had 2.36-times, 2.10-times, and 2.52-times enhancement compared to pristine devices without MNPs decoration. The primary results provide insights into the development of high-performance and wavelength-selective narrowband perovskite photodetectors.