Ask HN: How to store large amounts of data on paper with QR code like tech?

An old neighbour wants to settle his affairs - create a will, detail his investments, divide his assets among the kids etc. He asked me if it was possible to create a digital copy of all the documents (will, bank, title deed, investments, online account details etc.) and store it with some QR code like technology so that he can print all of it on a single sheet of paper and hand it to his kids. I remember reading there was some other tech (open source) that could store more data then QR, but I can't seem to recall or find it online. Any suggestions? (Let's not diverge on how there are alternate better solutions like archival disks etc).