LiFi Reception from Organic Photovoltaic Modules Subject to Additional DC Illuminations and Shading Effects

International audienceIn this paper, we study the performance of organic photovoltaic (OPV) modules as LiFi receivers in two specific configurations. The PV-based LiFi receiver is first exposed to an additional homogeneous light source with different intensity levels and then the influence of partial lighting is studied (shading effect). In both cases, we compare the sensibility and the cutoff frequency of LiFi transmission when the solar cell is operated either in short-circuit mode (i.e. when it is loaded with an active transimpedance amplifier) or in open circuit mode (i.e. when it is terminated with an high impedance passive load). While the OPV module performance decreases in open-circuit mode as a function of the DC illumination level, we observe an improvement of the cutoff frequency in short circuit mode. This result seems very promising for outdoor LiFi transmissions but also for indoor conditions where natural light can disturb LiFi communications. Theoretical explanations involving physical parameters for energy harvesting (carrier mobility, lumped series resistance) are proposed to justify the observed behaviors. Finally, experimental results of shaded solar cells are provided in the two operating modes (open-circuit and short-circuit). We show that sensibility and bandwidth of OPV modules strongly depend on both the shading configuration and the operating mode

LiFi Reception from Organic Photovoltaic Modules Subject to Additional DC Illuminations and Shading Effects

International audienceIn this paper, we study the performance of organic photovoltaic (OPV) modules as LiFi receivers in two specific configurations. The PV-based LiFi receiver is first exposed to an additional homogeneous light source with different intensity levels and then the influence of partial lighting is studied (shading effect). In both cases, we compare the sensibility and the cutoff frequency of LiFi transmission when the solar cell is operated either in short-circuit mode (i.e. when it is loaded with an active transimpedance amplifier) or in open circuit mode (i.e. when it is terminated with an high impedance passive load). While the OPV module performance decreases in open-circuit mode as a function of the DC illumination level, we observe an improvement of the cutoff frequency in short circuit mode. This result seems very promising for outdoor LiFi transmissions but also for indoor conditions where natural light can disturb LiFi communications. Theoretical explanations involving physical parameters for energy harvesting (carrier mobility, lumped series resistance) are proposed to justify the observed behaviors. Finally, experimental results of shaded solar cells are provided in the two operating modes (open-circuit and short-circuit). We show that sensibility and bandwidth of OPV modules strongly depend on both the shading configuration and the operating mode

Photovoltaic Solar Cells for Outdoor LiFi Communications

International audienceIncreasing demand of wireless devices contributes to radiofrequency (RF) congestion. Light Fidelity (LiFi) promises to be an interesting alternative by using the visible part of the electromagnetic spectrum instead of the RF part as nearly all existing wireless transmission systems do. A basic LiFi system is composed of one intensity-controlled light-emitting diode (LED) and one receiver device sensitive to very high-frequency (thus invisible to human sight) modulations of the luminous intensity. In most cases, the photoreceptor is a silicon photodiode of PIN (P-type intrinsic N-type) or APD (Avalanche photodiode) conception. Recently, a few studies suggest that photovoltaic (PV) modules could be used to implement outdoor LiFi transmissions, i.e., under direct sunlight exposure. In this paper, we propose to compare the behavior of a PV module and a commercial APD-based photodetector (without any optical lens or colored filter) for experimental LiFi transmissions on both indoor and outdoor conditions. The performance of the two solutions is quantified in terms of various frequency responses like attenuation, signal-to-noise ratio, or bit-error rate. The results show that, while the photodiode exhibits very good performance in indoor conditions, its frequency response is rapidly deteriorating when a sunlight exposure of more than 200W/m 2 is superimposed over the LiFi signal. We demonstrate that a PV module in Voc (open-circuit voltage) condition still operates a LiFi transmission under additional solar illumination