Filing activity in this dataset is concentrated among a handful of corporate and academic assignees, with the strongest co-filing relationships appearing between a major Korean electronics manufacturer and US and Korean university research groups. Recent-year momentum, however, shows most of the historically active assignees at zero new filings in the latest year, with only a Japanese national materials research institute showing continued growth. That combination — historical concentration but flat recent momentum — suggests the leadership list is more a record of past activity than a guide to who is filing today.

No, filing volume has been declining since a peak of 50 records in 2019, falling to 9 in the most recent partial year, with the 2022 midpoint at 44 marking the start of the downturn. Some of the drop in the final one to two years reflects normal publication lag rather than a real stop in filing. Taken together with the flat midpoint, the pattern points to a field that expanded through the late 2010s and has since settled rather than continuing to accelerate.

H10N (other electric solid-state devices) and H01L (semiconductor devices) carry the largest share of records, reflecting heavy claim activity on device and module architecture rather than materials chemistry alone. Alloys (C22C), non-metallic compounds (C01B), powder metallurgy (B22F) and ceramics (C04B) form a smaller materials-focused tail. A freedom-to-operate search that only checks H01L or H10N will miss meaningful prior art sitting in the materials classes.

US20090178700A1, assigned to Ohio State University Research Foundation, claims a doped Group IV/VI compound where the Group IV element occupies at least 95% of a defined sublattice, with doping restricted to a specified list of elements aimed at modifying the electronic density of states. It narrows the fenced territory to that specific sublattice-occupancy and dopant combination rather than to thermoelectric materials broadly. Compositions using different lattice structures or dopants outside the enumerated list, including nanostructured bulk approaches, fall outside its claim scope.

The thinnest branches by record count are conductor and insulator integration, other-metal compound chemistries, and ceramic or refractory substrate work for module durability — each represented by well under a tenth of the records seen in the core device classes. Only ten co-assignee pairs exist across the entire dataset, meaning most filers in these thinner branches are working alone rather than in joint programs. That combination of low volume and low collaboration density is where a differently scoped claim is most likely to find open ground.