IU is scheduled to feature in TaeYang's solo concert 'Solar' on the 25th and 26th of September. IU has previously revealed that she was a big fan of TaeYang and this was her dream come true.
This had happened thanks to Yoo In Na who is in a variety programme with IU currently. When she heard that they were looking for guests to perform at TaeYang's concert, she actively recommended IU.
TaeYang said "IU sings really well and it's great to see her grow up. I would be honoured to have IU sing at my concert"