Reliable Output Performance of a Photovoltaic–Piezoelectric Hybridized Energy Harvester with an Automatic Position-Adjustable Bending Instrument

In this work, we propose a rationally designed hybrid-bending instrument for reliably evaluating the functionality of a flexible photovoltaic–piezoelectric hybrid generator (PPHG) under simultaneously incident solar and mechanical energies. The deformation height of the PPHG is formulized and estimated on the basis of the geometric analysis of the bent PPHG to automatically calibrate the unexpected changes in experimental conditions during the simultaneous application of solar and mechanical stimuli. By using the proposed instrument, we successfully evaluate the performance of the PPHG and confirm that the developed instrument could prevent the over-evaluation of photovoltaic performance caused by the change in the height of the PPHG during mechanical bending. Thus, we objectively characterize the output behavior of the PPHG under simultaneously incident solar and mechanical stimuli. Our work in this study would contribute to developing an appropriate strategy for accurate characterization, which helps understand the underlying synergistic mechanism of hybrid energy harvesters.