Effectively Transparent Contacts for Thermally Sensitive Solar Cells using Low Temperature Reactive Silver Inks /

Abstract

There is great interest in minimizing the various losses caused by metal contacts in photovoltaic devices, in particular the optical and shadowing losses. In this study, a polymeric Polydimethylsulfoxide (PDMS) mold inscribed with a triangular microchannel pattern is used to deposit front metal contacts using a highly conductive, low temperature reactive silver ink (RSI) via capillary action. Fingers deposited with this technique exhibit a high aspect ratio, are optically narrow and ~ 85 % transparent. The resulting effectively transparent metal contacts (ETCs) can redirect incoming solar radiation to the photo-active area of the solar cell and mitigate parasitic absorption as well as shading losses. The use of RSI for the development of (ETCs) at low processing temperatures makes it possible for optoelectronic devices to include thermally sensitive layers. RSI exhibits high conductivity which is comparable to that of bulk silver if uniform films are deposited and anneals at ~100°C, making it suitable for devices that require low temperature processing. With the reduction of porosity upon addition of a suitable solvent and increasing compactness of these grid effectively transparent contact grid fingers, they have the potential to outperform their low temperature silver paste screen-printed counterparts in terms of both cost and efficiency and could even replace TCOs altogether.