Approaches for large-area a-SiC : H photovoltaic-powered electrochromic window coatings

We have fabricated 16 cm(2) monolithic, electrochromic (EC) window-coating devices powered by integral semitransparent amorphous silicon carbide (a-Si C:H) photovoltaics (PV). Self-powered PV-EC windows could modulate solar ga in in buildings, thereby reducing both heating and cooling requirements. In preparation for work on large-area PV-EC devices, we examined several impo rtant new issues. The first issue is control of pinhole shunt density in th e PV portion of the coating, and the second is resistive power loss in the transparent conductor contact layers. Adapting an electrochemical process p reviously demonstrated in a-Si:H, we have been able to electrically isolate shunts in our a-SiC:H devices. We propose a new design for scribing and bu s bar connections that can reduce the resistive losses on large area TCO wi thout greatly affecting window appearance. (C) 2000 Elsevier Science B.V. A ll rights reserved.