Arinna

Arinna makes solar cells out of transition metal dichalcogenides, atomically thin semiconductors that bend tighter than a pencil. The cell is built on a tungsten diselenide absorber a couple of hundred nanometres thick with graphene contacts, embedded in flexible polyimide. The pitch is that it needs no cover glass, which accounts for a significant share of the mass of a conventional space array, and that it can be made in weeks rather than the year or more a multi-junction order takes.

Koosha Nassiri Nazif and Alexander Shearer met in Eric Pop's laboratory at Stanford, and the company is a direct commercialisation of the work they did there. Their published result is the record for this class of material: 5.1 per cent conversion efficiency at 4.4 watts per gram. The efficiency is far below the thirty per cent or so that space-qualified triple-junction cells deliver, so the argument rests entirely on the second number, because watts per kilogram is what a spacecraft actually budgets.

The published science and the marketing claims are far apart. The company's own site advertises up to 32 per cent efficiency, roughly six times the published state of the art in this material system, with no intermediate result, paper or third-party measurement behind it. One report renders the same claim as 32 per cent better than current technology, which would mean something quite different. The ten-times power-per-mass figure is measured against glass-laminated terrestrial silicon rather than against what spacecraft actually fly. Radiation tolerance is asserted rather than published, and cover glass is not only there for radiation; it also handles atomic oxygen, ultraviolet and debris. The founders' 2024 paper on producing photovoltaic-grade material is titled toward mass production, which is an honest signal that making this at area and yield remains a research problem. Nothing has flown, and a CubeSat test is planned before the end of 2026.