A visible light communication (VLC) system using an organic bulk heterojunction photodetector (OPD) is presented. The system has been successfully proven indoors with an audio signal. The emitter consists of three commercial high-power white LEDs connected in parallel. The receiver is based on an organic photodetector having as active layer a blend of poly(3-hexylthiophene) (P3HT) and phenyl C61-butyric acid methyl ester (PCBM). The OPD is opto-electrically characterized, showing a responsivity of 0.18 A/W and a modulation response of 790 kHz at −6 V.

Visible light communication systems can be used in a wide variety of applications, from driving to home automation. The use of wearables can increase the potential applications in indoor systems to send and receive specific and customized information. We have designed and developed a fully organic and flexible Visible Light Communication system using a flexible OLED, a flexible P3HT:PCBM-based organic photodiode (OPD) and flexible PCBs for the emitter and receiver conditioning circuits. We have fabricated and characterized the I-V curve, modulation response and impedance of the flexible OPD. As emitter we have used a commercial flexible organic luminaire with dimensions 99 × 99 × 0.88 mm, and we have characterized its modulation response. All the devices show frequency responses that allow operation over 40 kHz, thus enabling the transmission of high quality audio. Finally, we integrated the emitter and receiver components and its electronic drivers, to build an all-organic flexible VLC system capable of transmitting an audio file in real-time, as a proof of concept of the indoor capabilities of such a system.

Halide perovskites (HPs) are promising materials for memristor devices because of their unique characteristics. In this study, nonvolatile resistive switching memory devices based on thick MAPbI₃ perovskite (800 nm) films with structure FTO/MAPbI₃/polymethyl methacrylate (PMMA)/Ag are presented. Reproducible and reliable bipolar switching characteristics are demonstrated with an ultra‐low operating voltage (−0.1 V), high ON/OFF ratio (10⁶), endurance (>2 × 10³ times) and a record retention time (>10⁵ s). The I–V curve of the first cycle exhibits self‐formed conductive filaments. These are attributed to the presence of metallic Pb resulting from an excess of PbI₂ in the perovskite film. The subsequent activation process involves the formation of conductive filaments, consisting of either iodide vacancies or migrated charged metals. Numerical simulations are then carried out to understand the nature of these conductive filaments and the role of the internal electric field in the migration of iodide ions, iodide vacancies, and Ag cations. Finally, an exhaustive model is proposed that explains the set and reset processes governing the first voltage cycle and the steady state, at different voltage ranges. In summary, this work offers a novel and thorough perspective of the complete resistive switching (RS) behavior in a MAPbI₃/buffer/Ag memristor, supported by numerical simulations.

The photoluminescence and mechanochromic behaviour of the bis(3-(3,5-bis(dodecyloxy)phenyl)-(5-pyridin-2-yl)pyrazolate)platinum(II) complex PT12, selected from a series of Pt(II) compounds with N,N′-pyridylpyrazolate ligands, has been investigated. The electroluminescence properties of polymer OLEDs based on PT12-doped polyfluorene (PFO) are also described. Addition of PT12 induces the formation of the PFO β-phase, a much more ordered phase with enhanced colour stability at high bias and high photoluminescence quantum efficiency. Additionally, the characteristic blue emission of PFO is red-shifted for PT12 concentrations equal to or higher than 3%. Depending on the dopant concentration and the applied current, the colour coordinates of these polymer OLEDs undergo a broad shift in the CIE colour space. In addition, through the strategic use of keto defect sites, white-emitting devices can be fabricated with a very small addition of PT12.

Organic solar cells (OSCs) based on Poly[N-9'-heptadecanyl-2,7-carbazole-alt-5, 5-(4', 7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (PCDTBT):1-(3-methoxycarbonyl)-propyl-1-1-phenyl-(6,6) C61 (PCBM) have been electrically dc and ac characterized. Device structure is ITO/Poly(3,4-ethylenedioxy-wthiophene)-poly(4-styrene sulfonate) (PEDOT:PSS)/PCDTBT:PCBM/C60MA/Al. Devices show the so-called S-shaped current-voltage curve that has been modeled with a circuit including two diodes in forward and reverse bias. Impedance measurements show one semicircle at low bias ( V <; 0.4 V) and two semicircles at ( V <; 0.4 V). Results reveal that the high-frequency semicircle is associated with the forward diode-like behavior of the dc circuit, while the low-frequency semicircle is associated with the reverse diode that causes the S-shape. The analytical solution of the dc two-diode circuital model has been fitted to the experimental I-V, and dc circuital parameters have been obtained. The ac equivalent circuit was derived from the dc circuit, and small-signal parameters have been calculated from the fits to the experimental Cole-Cole.