Colloidal PbS Quantum Dots for Visible-to-Near-Infrared Optical Internet of Things

Aigerim Tankimanova,Lutfan Sinatra,Boon S Ooi,Osman Bakr,Marat Lutfullin,Kai Wang,Omar Alkhazragi,Meiwei Kong,Chun Hong Kang,Xiao Wei Sun,Bing Xu,Haodong Tang,Shihao Ding,Depeng Li,Tien Khee Ng

doi:10.1109/jphot.2021.3066521

Abstract

The emergence of optical Internet of Things (optical-IoT) for sixth-generation (6G) networks has been envisaged to relieve the bandwidth congestion in the conventional radio frequency (RF) channel, and to support the ever-increasing number of smart devices. Among the plethora of device innovations deemed essential for fortifying the development, herein we report on the visible-to-near-infrared color-conversion luminescent-dyes based on lead sulphide quantum dots (PbS QDs), so as to achieve an eye-safe high-speed optical link. The solution-processed PbS QDs exhibited strong absorption in the visible range, radiative recombination lifetime of 6.4 $\mu$ s, as well as high photoluminescence quantum yield of up to 88%. Our proof-of-principle demonstration based on an orthogonal frequency-division multiplexing (OFDM) modulation scheme established an infrared data transmission of 0.27 Mbit/s, readily supporting an indoor optical-IoT system, and shed light on the possibility for PbS-integrated transceivers in supporting remote access control of multiple nodes. We further envisaged that our investigations could find applications in future development of solution-processable PbS-integrated luminescent fibers, concentrators, and waveguides for high-speed optical receivers.

Highlights

In the upcoming era of the Internet of Things (IoT), there is an ever-increasing demand for higher-speed, more power-efficient and secured data transmission to support various application scenarios
visible-light communication (VLC) is a promising technology for future indoor communications, there is a number of challenges that remain unresolved in the existing VLC or optical-IoT systems
To reduce the chances of blocking of the optical signal, and to increase the amount of the received light, the receiver area should be of larger size, while, at the same time, not be limited by the RC limits, such as in the prior work by Peyronel et al [4], in which the authors proposed a design of a flexible luminescent concentrator for free-space optical communication by utilizing optical fibers doped with visible fluorescent dyes

Summary

Introduction

In the upcoming era of the Internet of Things (IoT), there is an ever-increasing demand for higher-speed, more power-efficient and secured data transmission to support various application scenarios. VLC is a promising technology for future indoor communications, there is a number of challenges that remain unresolved in the existing VLC or optical-IoT systems One of such challenges is that high-speed photodetectors have small areas due to resistance-capacitance (RC) limits and so can only collect a small portion of the flux of photons, reducing the received signal power. In other works presented by Dong et al [5] and Manousiadis et al [6], fluorescent optical concentrators were aimed to increase the detection efficiency for the incoming visible-light signal, without degrading the field of view of the photodetectors Since these luminescent concentrators emit in the visible range, incorporating these materials into indoor optical-IoT systems will create undesirable illumination to the human eye in the long run under an indoor environment. Apart from the receiver end for downlink operation, the NIR luminescent dye could be integrated on optical-IoT systems for uplink operation based on visible-light sources, i.e., display screens, and omit the costly development path of NIR-based vertical-cavity surface-emitting laser (VCSEL) arrays

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Conclusion