Visible Elimination,
Ultraviolet and Near-Infrared Dual-Band Photodetector Based
on Single-Crystal
Perovskite Heterojunctions Toward Secure Optical Communication
Conventional photodetectors (PDs) sense either a broad
waveband
light or a selective narrow waveband light, which is plagued by indistinguishable
diverse wavebands and is not competent for the dual task of information
transfer and encryption in optical communication with an open light
transmitting channel. Dual-band PDs with the ability to sense two
discrete waveband lights have the potential to remedy the drawbacks
of single-band PDs and realize secure optical communication with a
straightforward optical encryption strategy. However, previous reports
of dual-band PDs usually relied on multistacked photosensitive layers,
which suffer from lattice mismatched interfaces contacting between
diverse semiconductor layers and complex device fabrication processes.
Herein, we propose a novel lattice-matched single-crystal perovskite
heterojunction (SCPH) through a facile and low-cost liquid-phase epitaxy
process. The fabricated dual-band PD with a structure of Au/MAPbCl3/Bi-MAPbBr3/Bi-MAPbI2.5Br0.5/MAPbI3/Au senses to a broad range of ultraviolet (UV)
light and a narrow range of near-infrared (NIR) light while blinding
to visible lights in between. At last, a chaos-based double-encrypted
secure optical communication system is built using the fabricated
UV/NIR dual band SCPH PD as an efficient receiver terminal, where
valid information is conveyed by UV and NIR light, respectively, and
further superimposed by visible light for separately encrypted transmission.
This work provides a facile method to fabricate visible-eliminating
UV/NIR dual-band PDs and offers new insights into security optical
communication without relying on complicated algorithms.