High-voltage photovoltaic micro-devices fabricated by a new laser-processing

Photovoltaic micro-devices that can generate more than 200 volts with an area of 1 cm2 have been developed to directly drive microactuators like such as piezoelectric or electrostatic actuators. The microdevices consist of 285 micro cells (unit cell size : about 0.5 mm X2.0 mm) interconnected threedimensionally. They generate an open circuit voltage (VJ of 207 volts, short circuit current (Is,) of 36.6,~ A, maximum output power (F",,) of 4.65mW and fill factor (F.F.) of 0.615 under AM (Air Mass) 1.5 and 100mW/cmz illumination. Each micro cell has an a-Si triple stack structure and generates a V,, of 2.3 volts and a short circuit current density (J,J of 6.5 mA/cm2. The series connection used for the micro cells is precisely processed by a focused lascr beam, thereby significantly reducing the area needed for connection on the devices. To evaluate the potential of the devices to be used as a microactuator's power source, it was necessary to investigate whether a piezoelectric polymer could be directly driven by their electrical output. This capability was confirmed.