The problem is that the version of JasperStarter used by PHPJasper to process the reports does not include the zxing library.
You have two options:
Download the zxing library jar file and put it into the same folder as the JDBC drivers
Use my fork version which upgrades JasperStarter to the latest version 3.6.2, which is in PR #311 pending review. See my comment in issue #299 for suggested changes to try my fork of PHPJasper before PR is accepted.
Really with the Jasperreports funtions all barcode types but not qr, is a bug?