arXiv subjects

Juan Ramon Sanchez-Valencia

Publications and source records attributed to Juan Ramon Sanchez-Valencia.

4 recordsLinked to original sources

arXiv2026

Adamantane plasma polymers: fluorine-free vacuum-processable triboelectric thin films for all-triboelectric nanogenerator configurations

Triboelectric nanogenerators (TENGs) are major drivers in on-site power generation for smart devices, enable self-powered sensors, and introduce novel catalytic processes. Here, we present the advantages of adamantane plasma layers as bivalently triboelectric surfaces capable of exhibiting both tribopositive and tribonegative character through simple modification of the synthesis conditions without the need for additives or functionalization. Fabrication facing or backfacing the plasma yields thin film polymers with different dielectric constants, Young's moduli, and secondary electron emission. The conformality, stability, and processability of the polymers enable direct implementation across solid-solid, solid-liquid, and hybrid piezo-triboelectric configurations. Additional texturization by buckling is shown to provide voltage and current outputs as high as 90 V cm2 and 0.6 uA for a 2.8 um (tribonegative) vs. 400 nm (tribopositive) combination. A maximum power density of 2.1 uW cm-2 is generated from salty droplets in a switch-electrode drop-TENG configuration employing a 500 nm-thick tribopositive adamantane polymer as the triboelectric surface. These layers have demonstrated outstanding durability, enabling more than 10^5 cycles in solid-solid nanogenerators and 10^4 droplet impacts in solid-liquid configurations. The synthetic method is environmentally friendly and industrially scalable, making the adamantane plasma polymer a reliable and competitive solution for thin film triboelectric materials.

cond-mat.mtrl-sci↗

arXiv2026

Water-resistant hybrid perovskite solar cell -- drop triboelectric energy harvester

Hybrid energy-harvesting systems combining perovskite solar cells (PSCs) with drop-driven triboelectric nanogenerators (D-TENGs) provide continuous power under various weather conditions. However, halide perovskites' vulnerability to moisture hampers widespread use. We present plasma-deposited fluorinated polymers (CFX) as multifunctional encapsulation layers offering water resistance, triboelectric functionality, and > 90 % optical transparency. These conformal, room-temperature, solvent-free coatings protect PSCs without reducing performance; encapsulated cells maintained a PCE of 17.9 %, and devices kept over 50 % of initial PCE after 10 days in high humidity and temperature. CFx layers also enabled compatibility with UV-curable resins, creating a hybrid PSC/D-TENG capable of harvesting solar and rain energy. This device retained 80 % of its performance after 300 hours of humid operation and stayed stable under continuous dripping and illumination for over 5 hours. Optimizing CFx's chemical composition improved triboelectric performance. Using the same CFx layer for encapsulation and triboelectric function, the device achieved 11.6 mA/cm2 short-circuit current under 0.5 sun and 12 V peak voltage per raindrop, enabling simultaneous solar and rain energy harvesting. A self-charging prototype powered LED arrays via a boost converter, demonstrating practical multisource energy harvesting.

cond-mat.mtrl-sci↗

arXiv2024

Triboelectric Pixels as building blocks for microscale and large area integration of drop energy harvesters

The ultimate step towards the exploitation of water as a clean and renewable energy source addresses the energies stored in the low frequencies of liquid flows, which demands flexible solutions to adapt to multiple scenarios, from raindrops to waves, including water moving in pipelines and microdevices. Thus, harvesting low-frequency flows is a young concept compared to solar and wind powers, where triboelectric nanogenerators have been revealed as the most promising relevant actors. However, despite widespread attempts by researchers, the drop energy harvesters' output power is still low, mainly because of the limitations in candidates endowed with ideal triboelectric and wetting properties and also the non-optimal and centimetre-scale device architecture that prevents the conversion of the complete kinetic energy of impinging drops. Herein, we disclose a microscale triboelectric nanogenerator that can harvest a high density of electrical power from drops through a single, submillisecond, long-lasting step. The mechanism relies on an instantaneous electrical capacitance variation owing to the high-speed contact of the drops with the electrodes' active area. We discuss the role of the precharged effect of the triboelectric surface in the time characteristic of the conversion event. The capacitive and microscale structure of the device is endowed with a small form factor that allows for the production of densely packed arrays. The proposed architecture can be adjusted to different liquids and scales and is compatible with a variety of triboelectric surfaces, including flexible, transparent, and thin-film approaches.

physics.app-ph↗

arXiv2023

Conformal TiO$_2$ aerogel-like films by plasma deposition: from omniphobic antireflective coatings to perovskite solar cells photoelectrodes

The ability to control porosity in oxide thin films is one of the key factors that determine their properties. Despite the abundance of dry processes for the synthesis of oxide porous layers, the high porosity range is typically achieved by spin-coating-based wet chemical methods. Besides, special techniques such as supercritical drying are required to replace the pore liquid with air while maintaining the porous network. In this study, we propose a new method for the fabrication of ultra-porous titanium dioxide thin films at room or mild temperatures (T lower or equal to 120 degrees Celsius) by the sequential process involving plasma deposition and etching. These films are conformal to the substrate topography even for high-aspect-ratio substrates and show percolated porosity values above 85 percent that are comparable to advanced aerogels. The films deposited at room temperature are amorphous. However, they become partly crystalline at slightly higher temperatures presenting a distribution of anatase clusters embedded in the sponge-like structure. Surprisingly, the porous structure remains after annealing the films at 450 degrees Celsius in air, which increases the fraction of the embedded anatase nanocrystals. The films are antireflective, omniphobic, and photoactive becoming super-hydrophilic subjected to UV light irradiation The supported percolated nanoporous structure can be used as an electron-conducting electrode in perovskite solar cells. The properties of the cells depend on the aerogel film thickness reaching efficiencies close to those of commercial mesoporous anatase electrodes. This generic solvent-free synthesis is scalable and is applicable to ultra-high porous conformal oxides of different compositions with potential applications in photonics, optoelectronics, energy storage, and controlled wetting.

physics.app-ph↗