Glitter-sized silicon photovoltaics add new functionality

Some thin-film or microsystem-based photovoltaic (PV) technologies with lateral dimensions on the order of 1 mm—for example, "Sliver" cells being commercialized by Origin Energy (Sydney, Australia)—benefit from reduced PV scaling through improved optical efficiency (carrier collection potentially improves with smaller dimensions), simplified thermal management (more favorable thermal gradients), and lower-cost module assembly (reusable substrates and low-temperature processing). Those scaling benefits are further amplified in new microscale glitter-sized PV materials developed by Sandia National Laboratories (Albuquerque, NM) and the National Renewable Energy Laboratory (Golden, CO), with lateral dimensions of just 250 µm.

Both gallium arsenide and crystalline silicon cells as small as 250 µm across and 14 to 20 µm thick with conversion efficiencies of around 10% were fabricated using traditional semiconductor photolithography and microelectromechanical systems (MEMS) processes; standard liftoff methods were used to remove the PV structures from their reusable substrates. The research team is currently exploring several module assembly techniques, including self-assembly through electrostatic, molecular, and capillary and surface-tension interactions. The small cells could be integrated into clothing for flexible and wearable PV applications, or incorporated in construction materials for building-integrated PV applications. Contact Vipin Gupta at [email protected].