Hybrid Plasmonic and Pyroelectric Harvesting of Light Fluctuations

Abstract

possess pyroelectric properties, including the leaves of the palm-like plant Encephalartos. [4] While the physiological implications of pyroelectricity in plants and other biomaterials are still poorly understood, [4,5] the effect can already be utilized in artificial devices for applications including light detection [2d,6] and energy harvesting. [3,7] Pyroelectric polymers have attracted considerable attention owing to their mechanical flexibility, easy processing, and low cost. [4,5] While there are a number of pyroelectric polymers, such as poly(vinylchloride) and Nylon 11, poly(vinylidene fluoride) and its copolymer poly(vinylidenefluoride-cotrifluoroethylene) (P(VDF-TRFE)) are particularly promising due to high pyroelectric coefficients and good chemical stability. [2a,c,d,8] Typical application areas for these polymers include heat sensing, thermal imaging, and fire alarms. [2a] In addition, these polymers have been significantly explored based on their piezoelectric properties to harvest mechanical energy. [3,9] Their combination with plasmonic nanostructures was only recently reported, for laser-based patterned phase-control of ferroelectric polymers. [10] However, plasmonic heating was, to our knowledge, not previously investigated for pyroelectric energy harvesting.Here, we present a concept that converts temporal fluctuations in sunlight to electrical energy. The device combines a plasmonic metasurface consisting of gold nanodisks with a thin organic P(VDF-TrFE) copolymer film. The plasmonic nanostructures strongly absorb light through resonant excitation of plasmons (collective charge oscillations), which leads to local heating of both the nanostructure and the surrounding environment. [11] Such light-induced plasmonic heating can enable a wide range of applications, including solar-powered autoclaving, [12] plasmon-driven thermophoresis, [13] seawater catalysis, [14] plasmonic-thermoelectric light detection, [15] and desalination concepts. [14] In our hybrid plasmonic-pyroelectric device (referred to as hybrid device below), plasmonic heating of a gold nanodisk array modulates the temperature of a pyroelectric polymer. The polymer then converts these temperaturechanges to electrical signals through the pyroelectric effect.We demonstrate the concept by designing a device that powers an external load connected to the hybrid device, and by characterizing its performance in detail. Combined optical and thermal simulations of the hybrid device are in agreement with State-of-the-art solar energy harvesting systems based on photovoltaic technology require constant illumination for optimal operation. However, weather conditions and solar illumination tend to fluctuate. Here, a device is presented that extracts electrical energy from such light fluctuations. The concept combines light-induced heating of gold nanodisks (acting as plasmonic optical nanoantennas), and an organic pyroelectric copolymer film (poly(vinylidenefluoride-co-trifluoroethylene)), that converts temperature changes into electrical sig...

Thermodiffusion‐Assisted Pyroelectrics—Enabling Rapid and Stable Heat and Radiation Sensing

“…Comparing Δ V pyro and Δ V iTE shows that the response time of the pyroelectric device (time to reach the peak value, around 8–12 s) is much lower than the response time of the iTE device (time to reach the saturated value, around 100–130 s). The change in charge density for the pyroelectric device upon a temperature change of 10 K is on the order of 3 nC cm −2 . This charge density is in the same range as that of the electric double layer (EDL) expressed by the iTE device when subjected to the same heat stimulus (14 nC cm −2 at T change = 10 K, Δ T = 2.8 K).…”

“…Initial heating (ii) leads to a rapid voltage increase due to reduced polarization over the film at higher temperatures. The voltage then quickly decreases back to zero due to re‐compensation by screened charge (iii) . The integrated device (bottom panels in Figure d) shows similar initial behavior upon heating (i).…”

“…As indicated by the arrows, the P(VDF‐TrFE) layer was negatively polarized, as true for all devices unless otherwise stated (also see Figure S1 in the Supporting Information). The copolymer P(VDF‐TrFE) is commonly employed for pyroelectric (and piezoelectric) sensing due to its light weight, high stability, and nontoxicity 7c,18. We measured changes in open‐circuit voltage (Δ V pyro ) while alternating the temperature ( T change ) of the pyroelectric device between 22 °C (room temperature) and 32 °C using a Peltier element.…”

“…Decreasing the temperature back to 22 °C led to similar signals with reversed polarity. These results are related to the temperature‐dependence of the polarization across the P(VDF‐TrFE) film, which leads to deficient or excess screened charges on the electrodes upon changes in temperature . At ambient environment, the open‐circuit voltage decreases to zero upon temperature equilibration due to rapid charge compensation and the signal becomes proportional to the rate change in temperature (details can be found in Section S2 in the Supporting Information).…”

“…Besides detecting heat induced by convection, it is important for human and artificial skin to be able to detect radiation by the sun. We equipped our integrated device with such capability by utilizing the strong light‐to‐heat conversion of plasmonic metasurfaces 1a,17a,18,21. Plasmonic metasurfaces are nanostructured metal surfaces that interact strongly with light via excitation of collective charge oscillations (i.e., plasmons).…”