# Progress of Organic/Inorganic Luminescent Materials for Optical Wireless Communication Systems
## 5 Concluding Remarks  
In this review, we highlighted the use of potential light converters with improved PL properties and color quality that are able to cover a wide range from the energy spectrum, thus facilitating data/information diffusion in optical wireless technologies. Mainly, the use of modified MOFs and conjugated polymer structures with modulable emission features (from green to orange-red color) constitutes an ideal option to extend the bandwidth of the data transmission to reach an efficient VLC process. Here, a maximum bandwidth of \(\sim\)430 MHz and efficient data rate of \(\sim\)1.6 Mbps were reached. Some limitations related to the lack of commercially available organic compounds with adequate PL properties, as well as the limited number of studies where these improved materials are incorporated as light converters, hindered their use in VLC. On the other hand, OLEDs achieved a significant advancement in their development by introducing conjugated polymer systems. This development increases the carrier mobility into the device, allowing it to obtain a frequency bandwidth and data rate value of 245 MHz and 1 Gbps, respectively. These features promoted the use of another kind of organic compound derived from BODIPY molecules, producing new organic light-emitting devices with white emission, as well as improved color properties, such as CRI of 95% and CCT of 4200 K. Unfortunately, low bandwidth values up to 50 MHz were reached, presenting a disadvantage compared to another light converter used for VLC technologies. Hence, a third option is the use of PNCs, the PL properties of which can be controlled through composition and particle size engineering (quantum confinement). At this point, the band gap can be modulated, giving a high possibility of obtaining a wider bandwidth for data transfer in VLC processes. Alternatives, such as the combination of cyan-emitting QDs with PNCs used as red-light converters to produce white color emission inks with PLQY \(\sim\)75%, favor the fabrication of WLEDs with CRI \(\sim\)95%. On the other hand, it is important to recognize the fact that for the fast radiative recombination dynamics of these nanocrystals, for instance, green-emitting PNCs, a maximum frequency bandwidth of 491.4 MHz were reported, which had one of the highest values achieved for VLC compared to standard phosphor-based converters. Nevertheless, the incorporation of iodide into PNCs to generate mixed halide CsPbBr\({}_{1.5}\)I\({}_{1.5}\) and synthesize pure CsPbI\({}_{3}\) nanoparticles favors the fabrication of high-speed white-light VLC systems, with a maximum bandwidth of \(\sim\)1000 MHz and a real-time data transmission of \(\sim\)1.7 Gbps. Some issues related to the material instability are also evident, with a crystalline phase transformation (\(\alpha\)-to-\(\delta\) phase) quenching the emission features of the perovskite. Here, encapsulation with a PMMA layer can hinder this transition and preserve the structural integrity of the light converter. From our point of view, the best option to expand the modulation bandwidth of VLC and increase the real-time data rate is through obtaining light converters capable of covering a broad range of the UV-vis-NIR. This outcome means that the coupling of different multicolor and stable luminescent organic species, or the use of confined PNCs with diverse halide composition (tunable band gap), are the most promising materials to provide efficient light-emitting devices that are suitable for future optical wireless applications. Conceptualization, writing--original draft preparation, writing--review and editing, [PERSON], [PERSON] and [PERSON]. Supervision, [PERSON]. All authors have read and agreed to the published version of the manuscript. [PERSON] is grateful for the FONDECYT Iniciacion fellowship 11230124 and Innova ConCiencia Consorcio Sur-Subantratico C2030 20 CEIN2-142146. I.O.-R. acknowledges the international collaboration project Innoving2030 16 ENI2-66903. Not applicable.