A flexible thin-film for powering stand alone electronic devices

This paper presents a flexible thin-film (FTF) composed by a photovoltaic (PV) cell, a flexible solid-state rechargeable battery and power management electronics. A flexible printed circuit board (fPCB) was used for providing physical support to the electronics and to the battery, whereas a PDMS (polydimethylsiloxane) layer was used for providing mechanical adhesion between the PV cell and the fPCB. The high elasticity of the PDMS makes this material an excellent candidate for adapting two materials with different thermal expansions (fPCB and PV). The physical measurements showed a prototype with a thickness in the range 1.52 ± 0.10 mm, 10 g of weight and 37 × 114 mm of size. The electrical measurements showed ability to provide an output voltage of 3.8 V in a continuously form under these conditions: the PV providing DC power for solar irradiations higher than 6 W m⁻², and the battery providing DC power for solar irradiations above bellow 6 W m⁻² (value that has emerged during the twilight between sunset and dusk).