Development of high-voltage photovoltaic micro-devices for an energy supply to micromachines

A submodule of photovoltaic micro-devices, which generates more than 200 volts with an area of 1 cm², has been developed to directly drive piezoelectric or electrostatic actuators which will be used as microactuators. The submodule consists of 95 microcells (each unit cell size is about 0.5 mm×2.0 mm) interconnected in series, and produces a submodule open circuit voltage (V_oc) of 207 volts, a short circuit current (I_sc) of 36.6 μ A, a maximum output power (Pmax) of 4.65 mW and a fill factor of under air mass 1.5, 100 mW/cm² illumination. Each microcell has an a-Si triple stack construction and produces V_oc of 2.3 volts, and short circuit current density of 6.5 mA/cm². The series connection for the microcells is precisely processed by a focused laser beam, thereby significantly reducing the invalid area of the submodule. The study confirms that a piezoelectric polymer can be directly driven by the electrical output of the submodule