How to make the default color theme in MUI transparent?

I wanted to set the background color of an element to be the primary main color but with transparency using Material-UI, tried to do it the following ways but both hasn’t worked , any suggestion i would highly appreciate it.

backgroundColor: `rgba(${theme.palette.primary.main}, 0.6)`,

&

background: `rgba(${theme.palette.primary.main}, 0.6)`,