Improved monolithic photovoltaic-electrochromic devices incorporating an a-SiC:H solar cell

In the tandem photovoltaic-electrochromic (PV-EC) device, a wide-gap, semitransparent, amorphous silicon-carbon alloy (a-SiC:H) photovoltaic device and an electrochromic optical transmittance modulator (EC device) are deposited sequentially to form a monolithic device on a single substrate. This device can be used as a ''smart'' window for active control of daylighting and building cooling load without an external electrical connection. Last year we reported preliminary results on our development of a semi-transparent PV cell incorporating an a-SiC:H i-layer. Here we report our recent progress on the semitransparent PV component of a PV-EC device and development of a Li-based EC device that colors at voltages below 0.9 V. Finally, we discuss both recent progress and difficulties in integrating the two devices on one substrate.