'My co-author is based in North Korea'

Aron Walsh has never met his collaborators; so far, their only contact has been via email. He’s never even spoken to them on the phone. A picture he tracked down on the internet is the only reason he has a rough idea of what they look like. That’s because his co-authors live in North Korea.

Walsh leads the materials design group at Imperial College London, UK. ‘I work on perovskite solar cells, a topic that has attracted global interest,’ he explains. ‘But I noticed that some of my papers had been cited by a group with an affiliation in North Korea, which made me a little bit curious because I wasn’t really aware that mainstream research in the physical sciences was being conducted there.’