Hi and welcome
When you use the EXE outside of the compiler,
it need to have some DLLS
in order to run. (in the same folder as the exe)
please see
http://doc.qt.io/qt-5/deployment.html
for short list
http://www.bogotobogo.com/Qt/Qt5_Deploy_Windows_Plugins_Platforms_qwindows.php
and for the best:
http://www.tripleboot.org/?p=138

You can also use
http://www.dependencywalker.com/

to cast some light one if you need other dlls.