Improving the data rate for long distance visible light communication using h-BN/CdZnSeS@ZnSeS quantum dot composite

Quantum dots (QDs) are exploited in visible light communication (VLC) due to their unique optical properties. However, it is still a challenge to conquer heating generation and photobleaching under prolonged illumination. In this paper, we proposed to utilize hexagonal boron nitride (h-BN) nanoplates to improve the thermal stability and photo stability of QDs and long-distance VLC data rate. After heating to 373 K and cooling to the initial temperature, photoluminescence (PL) emission intensity recovers to 62% of the original intensity and after 33 hours of illumination, PL emission intensity still maintains 80% of the initial intensity, while that of the bare QDs is only 34% and 53%, respectively. The QDs/h-BN composites perform a maximum achievable data rate of 98 Mbit/s by applying on-off keying (OOK) modulation, while the bare QDs are only 78 Mbps. In the process of extending the transmission distance from 0.3 m to 5 m, the QDs/h-BN composites exhibit superior luminosity corresponding to higher transmission data rates than bare QDs. Particularly, when the transmission distance reaches 5 m, the QDs/h-BN composites still show a clear eye diagram at a transmission rate of 50 Mbps while the eye diagram of bare QDs is indistinguishable at 25 Mbps. During 50 hours of continuous illumination, the QDs/h-BN composites keep a relatively stable bit error rate (BER) at 80 Mbps while that of QDs continuously increase, and the -3 dB bandwidth of QDs/h-BN composites keep around10 MHz while the bare QDs decrease from 12.6 MHz to 8.5 MHz. After illumination, the QDs/h-BN composites still indicate a clear eye diagram at a data rate of 50 Mbps while that of pure QDs is indistinguishable. Our results provide a feasible solution for realizing an enhanced transmission performance of QDs in longer-distance VLC.