Narrowband Blue Light Optoelectronic Synapses With aJ‐Level Energy Consumption and Ultra‐Narrow FWHM for High‐Accuracy Fingerprint Identification

ABSTRACT Non‐destructive identification of latent fingerprints is vital for criminal investigations. Sebum‐rich fingerprints can emit 440 nm blue fluorescence upon deep‐ultraviolet light excitation, offering an opportunity to discriminate them via optoelectronic detection means. Here, a narrowband optoelectronic synapse is designed based on a PEA 2 PbBr 3.5 I 0.5 /PTAA heterostructure, which can perceive 440 nm optical information with the ability to suppress background noise of other non‐target wavebands. A sufficiently thick PTAA film functions as a hole‐conducting channel and an ultraviolet light attenuating layer. Plus, B 4 PyMPM as electron capture sites enhances spatial separation of photocarriers. Consequently, the device attains improved synaptic behaviors within a narrow waveband of 395–465 nm, featuring a full width at half maximum (FWHM) of only 44 nm. Primarily, it operates with an exceptionally low power consumption of only 7.40 aJ per synaptic event and holds prominent cycling durability and long‐term stability. Additionally, the FWHM can be further narrowed down to 18 nm by halide composition engineering. Finally, thanks to the excellent narrowband synaptic properties, the device is employed to pre‐process fingerprint data for fingerprint identification, showing a high accuracy of 97.8%. This study opens the door to the design of narrowband optoelectronic synapses for specific applications.