Travelling to Malaysia with an iPhone

I'm planning on purchasing a new iPhone soon because my current one is almost gone. However, I'm travelling to Malaysia in September and I was told by a relative that because of the different wattage in Malaysia in comparison to Australian wattage it can stuff up the phone and the screen can be ruined (I was told that a big purple line can appear on the screen).

Should I purchase the phone and take it overseas if this can happen by chance or if this wattage difference problem is guaranteed or should I wait until I get back and purchase a cheap phone to take over there?