Encryption and Shortcode for Visible Light Communication Based on the ZnO/PVK/Cu ₂ O/FTO Bipolar Response Photodetector

As the core of a wireless interconnection system, optical communication plays a vital role in modern communication technology. The traditional photodetector (PD) is an important component of the receiving end, its photoresponse polarity is single, which cannot selectively identify the spectrum, and the complex and cumbersome configuration of the encryption system seriously restricts its further development. In this paper, we report a ZnO/organic polymer poly(<i>N</i>-vinylcarbazole) (PVK)/Cu₂O/FTO heterojunction PD, which successfully achieves wavelength-dependent bipolar response output under zero bias by combining the bidirectional driving force of heterojunction and Schottky junction and reasonable band structure design. In the self-made simple optical communication system, 540 and 460 nm LED lamps that match the commercial RGB emission spectrum are used as the signal source, and the positive polarity valid signal is well hidden by the negative polarity key signal, to encrypt the information. By modulating the two signal sources, the ASCII code can be simplified to half of its original size, which has extraordinary significance for improving the data transmission speed. In addition, we have implemented the execution of multifunction optoelectronic logic gates (OLGs). This study provides a new idea for the design of bipolar response PDs and their application in emerging fields, such as visible light communication.