I have an url that contains this
Well, you'd do good to look at the HTML for this page then:
<a href="/questions/38720183/how-can-i-display-%c3%ab-character-in-the-url" class="question-hyperlink">How can I display ë character in the url?</a>
You must use the correctly URL-encoded version,
%c3%ab. The browser may then decide to render it as "ë". That's entirely up to the browser, and it won't do it for all characters, specifically it won't decode particular lookalike characters which can be used to spoof a URL to look identical to another URL but actually be different.