PHP's "characters" are 8-bit. If you want to output a character with a code higher than 128, you'll need to specify an encoding that supports that character, then output the codes that that encoding requires.
If you set UTF-8 encoding, for example, you'd print "\xE2\x80\x8B"
.
Of course, if this is HTML, you can typically use the HTML entity ref ​
as well, which wouldn't require changing the page's encoding.