Photo-mobile polymers in energy harvesting applications under simulated solar light

Abstract

Azobenzene-based photo-mobile polymer (PMP) samples were mechanically coupled with foils of piezoelectric material (PZM) and placed under a solar simulator. The solar simulator used a short arc xenon lamp as a light source with an AM1.5 filter o mimic the absorption spectrum of earth’s atmosphere. This setup, commonly used for testing solar cells (at a power density of 1000W/m2), was used to verify the energy generation capabilities of a PMP-PZM system. As shown in previous works, the movement of the PMPs can be attributed to a narrow spectrum of light near the UV range while heat or light outside of that narrow band can prove detrimental to the motion. Thus, to verify operation under "natural light" various methods filters are employed to the solar simulator light. The output of the PZM was loaded with a constant resistance and the voltage across the load was measured using a high impedance buffer amplifier to eliminate any other loading effects. While it was shown that any optical filters that removed the UV component lead to completely stopping the PMP motion, the system was capable of operating in direct sunlight and generated measurable energy on the load. Peak voltage of over 4V was achieved and discharged an average of 710nJ over a 50s period. This result could be significantly improved, but was limited by the mechanical capabilities of the shutter.