When it comes to composing their catchy riffs, AC/DC use basic, open chord almost exclusively. 'Back in Black' comprises some of the first open chord shapes guitarists learn, E, D & A.
"We tend to stay down that end of the neck, it’s easier for us to reach! Actually, it’s the sound quality of open chords that’s the thing. They’re big sounding, and they ring for ages if you want them to. You could take any one of our songs and play it with barre chords, but you would lose width and depth."